ABO TYPING (blood)
ABO typing is done to determine your blood type. Are you A, B, AB or O? It is done as part of a blood transfusion, organ or bone marrow donation/transplant, or paternity test. For people who simply want to know their own blood type, we suggest discussing with your physician who may give you a test requisition, but there is a fee that you’ll have to pay since it is not covered by the BC medical plan.
ALBUMIN (blood, urine)
Albumin is a protein comprising half of all the protein in the serum. Albumin regulates the pressure in tissues (oncotic pressure), serves as a nutritional source, and carries toxins and metabolites in the blood stream. It is low in severe nutritional deficiency, chronic liver disease, and nephrotic syndrome.
ALCOHOL (blood, urine)
Alcohol (ethanol, ethyl alcohol) can be detected and quantified in body fluids. Following alcohol consumption, blood levels decline at 150 mg/L/h. Alcohol cannot be reliably detected in the urine beyond about 6-8 hrs.
ALDOSTERONE (blood, urine)
Aldosterone is a substance manufactured by the adrenal glands that controls salt balance. A tumor in the adrenal gland can produce aldosterone in excess and this will cause high blood pressure. For more information, see the section on Adrenal Disease.
ALKALINE PHOSPHATASE (blood)
Alkaline Phosphatase (ALP) is an enzyme produced by the liver and bone. ALP activity is increased in bone disorders and obstructive (cholestatic) liver disease.
ALPHA - 1 ANTITRYPSIN (blood)
Alpha-1 Antitrypsin is an enzyme that inactivates the protein-degrading enzyme trypsin and prevents it from damaging tissues. A genetic defect (A1AT deficiency) causes liver disease and lung disease.
ALANINE AMINOTRANSFERASE (blood)
Alanine Aminotransferase (ALT) is a liver enzyme that is increased in inflammation of the liver. Minor increases are seen with “flu” and major increases (500-3000) are seen in hepatitis.
ALPHA THALASSEMIA TESTING (by PCR)
Detection of major deletions and point mutations associated with alpha thalassemia using molecular technologies. The method detects the 3.7, 4.2, SEA, MED, FIL, THAI, 20.5, Quong Sze and Constant Spring mutations.
AMYLASE (blood, urine)
Amylase is a digestive enzyme produced by the pancreas. In a disorder known as pancreatitis, the pancreas becomes inflamed and causes severe abdominal pain as well as elevated levels of serum and urine Amylase.
Androstenedione is an androgen (male hormone) produced by the adrenal gland (and to some degree by the ovary). It is a useful test for evaluation of hyperandrogenism, CAH and premature adrenarche.
ANGIOTENSIN CONVERTING ENZYME (blood)
Angiotensin Converting Enzyme (ACE) is used to help diagnose and treat Sarcoidosis (a lung condition). It can be abnormal in other lung diseases.
ANTIBIOTIC SUSCEPTIBILITY TEST
If bacteria are found when a swab is cultured, a sample of the bacteria can be grown on a separate culture plate. Small discs (like confetti) that have been soaked with various antibiotics are also placed on the culture plate. The lab can then tell which antibiotics are most effective against the bacteria.
ANTICARDIOLIPIN ANTIBODY (blood)
The presence of antibodies to cardiolipin, a component of cell membranes, may lead to excessive blood clotting. This can cause strokes, blocked blood vessels, and intrauterine fetal death.
ANTI-DNA ANTIBODY (blood)
Anti-DNA is an autoantibody (antibody produced against the patient’s own tissue) whose presence is strong evidence for Systemic Lupus Erythematosus (SLE). A negative test does not rule out this diagnosis. For more information, see the section on Lupus.
APOLIPOPROTEIN A-1 (blood)
Apolipoprotein A-1 is the protein associated with HDL-Cholesterol (“good cholesterol”) particles. Like HDL, low values are one of the most reliable predictors of Coronary Atherosclerotic Disease (CAD).
APOLIPOPROTEIN B–100 (blood)
Apolipoprotein B-100 is the major protein that makes up all of the lipoproteins other than HDL. Apolipoprotein B-100 is the major constituent of LDL-Cholesterol. Increased levels are associated with a higher risk of Coronary Atherosclerotic Disease (CAD). It is typically measured with a standard lipid panel only when the triglyceride level is high.
ASPARTATE AMINOTRANSFERASE (blood)
Aspartate Aminotransferase (AST) is a liver enzyme that is increased in inflammation of the liver. Minor increases are seen with “flu” and major increases (500-3000) are seen in hepatitis. As the test is not very specific, follow-up is typically not recommended unless values exceed 1.5 times the upper limit of normal.
BETA 2 MICROGLOBULIN (blood)
Beta2-microglobulin (BMG) is a low molecular weight protein related to the immunoglobulins. It is increased in various malignant and immune disorders where it is produced proportionally to the tumour load, disease activity and prognosis. It is also increased in chronic inflammation, liver disease, acute viral disease, renal failure, and chronic cadmium exposure (a good industrial marker) – urine values increase. BMG can be used in assessing renal function, particularly in kidney-transplant recipients and in patients suspected of having renal tubular disease. It also can serve as a nonspecific but relatively sensitive marker of various neoplastic, inflammatory, and infectious conditions. Early hopes that it would be a useful serum test for malignancy have not been fulfilled, but it does have prognostic value for patients with lymphoproliferative disease, particularly multiple myeloma. More recent reports have suggested a role for BMG as a prognostic marker in human immunodeficiency virus (HIV) infection.
BETA NATRIURETIC PEPTIDE (blood)
Beta natriuretic peptide (BNP) is used to evaluate cardiac function in the investigation of heart failure. LifeLabs performs the BNP test only, not NT-proBNP.
Bicarbonate is the main acid buffer in the blood stream. Low values occur in metabolic acidosis and respiratory alkalosis. High values occur in metabolic alkalosis and respiratory acidosis.
BILIRUBIN, DIRECT/CONJUGATED (blood)
Bilirubin is the end result of hemoglobin breakdown and is removed from the body by the liver. Increased bilirubin comes from liver disease or from increased hemoglobin breakdown. Bilirubin is then chemically modified in the liver to the direct (or conjugated) form that is more readily eliminated by the body. Thus, an increase in the direct/conjugated fraction indicates an obstructive liver disorder. See Bilirubin (Total) below.
BILIRUBIN, TOTAL (blood)
Bilirubin is the end result of hemoglobin breakdown and is removed from the body by the liver. Increased bilirubin comes from liver disease or from increased hemoglobin breakdown. Bilirubin is increased in the serum in the following disorders:
•hemolysis i.e. excessive breakdown of red cells
•obstructive liver disease (bile duct obstruction or cholestasis), where the bilirubin is conjugated in the liver but is not removed. Thus the conjugated or “direct” bilirubin is raised.
•hepatocellular disease e.g. hepatitis, alcoholism
To assess the ability of the body to control bleeding, a test is performed by cutting the skin and timing how long it takes to stop bleeding. This is now an obsolete test.
To determine if bacteria are growing in someone’s blood stream, a sample of blood is removed and placed in a bottle of nutrients. It can then be examined at intervals to see if bacteria have grown.
C - REACTIVE PROTEIN (blood)
C-Reactive Protein (CRP) is a protein that increases in response to inflammation. Recent evidence has suggested that the high sensitivity CRP test (hsCRP) may be useful in predicting heart attacks. All samples referred to LifeLabs for CRP are analyzed using an hsCRP method. For more information, see the section on Lipid Testing.
CA 125 (blood)
CA 125 is a tumour marker of ovarian cancer. The CA-125 molecule is widely distributed on the surface of both healthy and malignant cells of mesothelial origin including pleural, pericardial, peritoneal and endometrial cells, as well as in the normal genital tract and amnionic membrane. It is not a screening test for ovarian cancer; rather, it is used to monitor ovarian cancer following treatment. CA-125 is increased in many patients with ovarian cancer; the proportion rises with cancer stage. Values > 35 U/L are predictive of intra peritoneal tumor or recurrence. Benign conditions associated with CA-125 increase includes: menstruation, pregnancy, benign pelvic tumors, pelvic inflammatory diseases, ovarian hyperstimulation syndrome, endometriosis, peritonitis and many diseases leading to pleural effusion or ascites. CA-125 values of up to 5000 unit/mL have been reported in some benign conditions.
CA 15-3 (blood)
CA 15-3 is a protein (also known as Breast Cancer Mucin) that is produced by many cancers of the breast. It is not a screening test for breast cancer; rather, it is used as a follow-up after breast cancer has been treated. This may allow a relapse to be detected before becoming clinically apparent.
CA 19-9 (blood)
CA 19-9 is a tumour marker of gastrointestinal malignancies such as cholangiocarcinoma, pancreatic cancer and colon cancer. It is not a screening test; rather, it is used as a follow-up after the initially diagnosed tumour has been treated. This may allow a relapse to be detected before becoming clinically apparent.
CALCIUM (blood, urine)
Serum calcium levels are held within tight limits in the blood by a complex sequence of hormones. Increases in serum calcium are seen with: parathyroid adenoma, pheochromocytoma, lymphoma, parathyroid carcinoma, tertiary hyperparathyroidism (chronic renal failure), PTH secreting tumours, metastatic carcinoma to bone (breast, lung, kidney, lymphoma, leukemia), vitamin D overdosage, multiple myeloma, tumour producing a hormone that acts like PTH but does not cross react in the assay (parathyroid hormone related peptide (PTHrP)), sarcoidosis, milk alkali syndrome, Paget’s disease, thyrotoxicosis, acromegaly, and acute tubular necrosis.
Some reasons for a low calcium are low albumin, decreased PTH, PTH insensitivity (pseudohypoparathyroidism), vitamin D deficiency (due to diet or malabsorption), low dietary calcium, calcium malabsorption, chronic renal failure, magnesium deficiency, anticonvulsant therapy, acute pancreatitis, massive blood transfusion, osteomalacia, renal disease, liver disease, diuretics, increased serum phosphate (e.g. due to renal insufficiency) and hyperadrenalism.
The urine calcium is measured to determine if the body is losing more calcium than normal. High urine calcium also poses a risk for calcium kidney stones.
CAMPYLOBACTER (by PCR)
Campylobacter species are the most common cause of bacterial diarrhea, and also cause abdominal pain, fever, headaches and sometimes vomiting. Molecular methods provide rapid sensitive identification of the most clinically important group of Campylobacter species.
Carbamazepine (Tegretol) is a drug used to treat seizures. Decreased values are seen with Phenobarbital and Phenytoin, both of which increase carbamazepine metabolism. Measurement is carried out to adjust the dosage. For more information, see the section on Therapeutic Drug Monitoring.
A copper-containing protein, ceruloplasmin is markedly decreased in Wilson’s disease, a genetic condition in which copper deposits in the liver, brain, and eye. This test is most helpful in younger patients with otherwise unexplained liver disease.
Cholesterol is a blood lipid whose levels correlate with the risk of heart and artery disease. There are two principal forms of cholesterol: low-density lipoprotein (LDL) and high-density lipoprotein (HDL). HDL is the “good” cholesterol removed from blood vessels while LDL represents the “bad” cholesterol most directly related to the risk of heart disease. HDL cholesterol and total cholesterol are measured directly but LDL cholesterol is obtained by calculation. In BC, Cholesterol testing is governed by a Protocol developed by the Medical Services Commission and the BCMA. For more information, see the section on Cholesterol.
Chlamydia is a microorganism species that causes a variety of diseases. Most often it is studied in genital cultures or urine, as it is a common sexually transmitted disease (STD).
CHLORIDE (blood, urine)
One of the principal electrolytes in the blood stream, chloride is an ion whose negative charge balances positively charged sodium and potassium.
There are two types of cholinesterase test. The form found in red blood cells is used to detect exposure to organophosphorus insecticides, but is not currently available in BC. The serum cholinesterase test is used to determine whether a patient can break down the muscle paralyzing drugs that are used in anesthetics.
Citrate is a substance excreted in the urine. Low urine citrate concentrations increase the risk of kidney stones.
Sometimes when antibiotics are taken orally they disrupt the normal bacteria in the bowel and allow bacteria known as Clostridium difficile to grow. C. difficile produces a toxin that can cause diarrhea.
C. DIFFICILE (by PCR)
Molecular testing for C. difficile allows rapid and simultaneous identification and detection of genes for toxin A and toxin B, both associated with diarrhea.
Clozapine (Clozaril®), a tricyclic dibenzodiazepine, is used for the symptomatic management of psychotic disorders and is considered an atypical antipsychotic drug. It is currently used primarily for the treatment of patients with schizophrenia or schizoaffective disorders who are at risk for recurrent suicidal behavior and who have encountered nonresponse or adverse, intolerable extra-pyramidal side effects with more classical antipsychotics (chlorpromazine, haloperidol). For more information, see the section on Therapeutic Drug Monitoring.
COLD AGGLUTININS (blood)
A number of diseases result in the production of IgM antibodies (occasionally IgG) that coat red blood cells. They are so called because their optimal action in causing red cell damage is at temperatures lower than 37°C. The test is used in the diagnosis of Hemolytic anemia. Cold agglutinins are found in a number of disorders: Idiopathic (unknown causes) 25%, drug induced (15%), neoplasia 15% (lymphoma, leukemia, carcinoma), infections 10% (mycoplasma, viral pneumonia, infectious mononucleosis), collagen diseases 2% (SLE, Rheumatoid arthritis), and other 5%. cold hemaglutinin disease (IgM mediated) usually occurs in persons over 50 y (women more common than men). Patients may present with acrocyanosis, Raynaud’s, or even hemolysis following exposure to the cold.
COMPLEMENT C3 and C4 (blood)
The complement system consists of an interacting group of circulating proteins that mediate the inflammatory response and help to destroy foreign particulate matter (particularly microorganisms and viruses). The complement proteins circulate as inactive precursors that become activated in a precise sequence that allows mediation of their collective response.
C3 is one of the “routine” complement tests. Patients with homozygous C3 deficiency have an increased incidence of bacterial infections. A decrease in C3 is associated with complement fixing disorders: acute glomerulnephritis, membranoproliferative glomerulonephritis, immune complex disease, and active SLE. C4 is part of the classical pathway of complement. C4 measurements are used with C3 to determine which pathways have been activated. Value is low in: SLE, early glomerulonephritis, immune complex disease, cryoglobulinemia, and Hereditary Angioneurotic Edema.
COPPER (blood, urine)
Copper in serum is measured to confirm a diagnosis of Wilson Disease, though ceruloplasmin or 24h urine copper are more helpful (see discussion on Ceruloplasmin).
CORTISOL (blood, urine)
Cortisol is the main product of the adrenal gland. Excess cortisol production is called Cushing’s Syndrome. Inadequate cortisol production is called Addison’s syndrome. Increased values are seen in adrenal tumour, pituitary tumour, stress, depression, hypoglycemia, and some drugs (hydrocortisone, methylprednisolone). Decreased values are seen in adrenal failure, pituitary insufficiency, and some drugs (prednisone, dexamethasone). For more information, see the section on Adrenal Disease.
CREATINE KINASE (blood)
Creatine kinase (CK) is a muscle enzyme that is released into serum in any form of muscle disease or trauma. Levels are particularly high in myositis / dermatomyositis and JRA. Increases are also seen in myocardial necrosis (heart attack), strenuous physical exercise, surgery, burns, alcoholic myopathy, alcoholic withdrawal syndrome, low potassium levels (hypokalemia), hypothyroidism, renal failure, obstructive lung disease, pneumonia, and infections. Binding of immunoglobulins to CK (“macro-CK”) may result in falsely elevated results.
CK-MB is a form found primarily in heart muscle, from which it is released following a heart attack. The test for CK-MB, though, has been largely replaced by cardiac Troponin, which is both more sensitive and specific. The CK-MB index, reported along with CK-MB, is defined as the percentage of CK-MB activity relative to total CK.
CREATININE (blood, urine)
Creatinine is a waste product of muscle metabolism. It is produced by the body in rough proportion to the amount of muscle present. It is then removed by the kidney. Increases in serum creatinine are due to increased production (rapid muscle breakdown, fever, burns, trauma) or decreased removal (kidney failure).
Urine creatinine is measured to check for a complete 24hr collection or, for random collections, to correct for normal urine dilution.
A peculiar form of fibrinogen (a clotting protein) that coagulates when the blood drops below 37 degrees C.
Cryoglobulins are protein complexes which precipitate at temperatures below normal body temperature (usually 4° C). Patients may suffer from cold induced precipitation of protein in small, peripheral blood vessels causing vascular purpura, bleeding, urticaria, Raynaud’s, pain and cyanosis. Some patients have Essential Mixed Cryoglobinemia that presents with purpura, arthralgia, weakness, lymphadenopathy, hepatosplenomegaly, and adrenal failure.
C-telopeptide (CTX) is a degradation product of collagen. The test is used for bone fracture risk assessment, osteoporosis medication monitoring and prediction of risk for osteonecrosis of the jaw. At present, the test is not publicly funded in BC.
CTX patient brochure; CTX physician brochure
CULTURE FOR DERMATOPHYTE
Scrapings from skin lesions are grown on gelatin media to identify any skin fungi that may be present.
Cyclosporine A is a drug used in organ transplant patients that reduces the “rejection” of the transplant. It acts by interfering with interleukin-2 (a growth factor for T-lymphocytes). It is measured to keep the cyclosporine level in the therapeutic range but below toxic levels. For more information, see the section on Therapeutic Drug Monitoring.
D-dimer is a fibrin degradation product, a small protein fragment present in the blood after a blood clot is degraded by fibrinolysis. D-dimer concentration is determined by a blood test to help diagnose thrombosis. Since its introduction in the 1990s, it has become an important test for patients suspected of thrombotic disorders, eg. deep venous thrombosis (DVT) or pulmonary embolism (PE). In patients suspected of disseminated intravascular coagulation (DIC), D-dimers may aid in the diagnosis. While a negative result practically rules out thrombosis, a positive result can indicate thrombosis but does not rule out other potential aetiologies. Its main use is to exclude thromboembolic disease where the probability is low.
DEOXYPYRIDINOLINE CROSSLINKS (urine)
Deoxypyridinoline crosslinks are the waste products of normal bone degradation. The amount found in the urine is directly related to the rate at which bone is being degraded. For more information, see the section on Osteoporosis.
DHEAS (Dehydroepiandrosterone sulfate) is the main metabolite of DHEA, the principal androgen (‘male hormone’) of the adrenal gland. Its measurement is a good indicator of whether the adrenal gland is producing too much androgen. DHEA has gained popularity (though not in the medical community) as a substance that may increase muscle strength and general energy and vigor.
A heart drug that helps the contraction of the heart muscle. There is very little difference between the blood concentration where therapy is optimal and where toxicity can occur. For more information, see the section on Therapeutic Drug Monitoring.
DRUG SCREEN (urine)
A group of tests carried out to detect the presence of drugs of abuse (cocaine, heroin, morphine, amphetamines, cannabis, etc.). These tests are intended to detect as many compounds within one group as possible: they do not identify which compound is present. This information is provided by a Confirmation test, often referred to as ‘GC/MS’ (the name of the technique used). Note that these tests are not suitable for medicolegal purposes unless prior arrangements have been made with LifeLabs.
*) Drug either non-reactive or typically at levels below test cutoff for positive.
Detection Window (d)
Related Drugs Not Detected
BC MSP Metha-done Panel
BC MSP Medical Drug Screen
MDA (‘Ecstasy’ metabolite)
1 – 3
3 – 5
(to 42d for chronic)
Up to 30
Benzoylecgonine (cocaine metabolite)
3 - 5
EDDP (methadone metabolite)
6 – 7
2 – 3
More information about drug testing at LifeLabs
ENTERIC PATHOGENS (by PCR)
Enteric pathogens are a group of microorganisms such as Salmonella or E. coli that cause a variety of gastrointestinal symptoms such as diarrhea. Molecular methods allow rapid and simultaneous identification of major enteric pathogens or the detection of genes for toxigenic agents associated with diarrhea.
EXTRACTABLE NUCLEAR ANTIGENS (blood)
In certain autoimmune diseases the body forms antibodies to proteins found in the nucleus. The extractable nuclear antigens (ENA) test consists of an examination for auto-antibodies to proteins known as Sm, RNP, SS-A, SS-B, Scl 70 and Jo-1. The interpretation of this panel is outlined below:
- Sm A: confirmatory test for SLE if the patient has an increased ANA and aDNA. Often heralds CNS or renal complications).
- RNP: positive in 35 – 40 % of persons with SLE. Also + in Mixed Connective Tissue Disease (if RNP is the only antibody positive then renal complications are less likely).
- SS-A (Ro): positive in 25% of SLE patients. Positive in 40% of Sjogren’s Syndrome. Also positive in Antibody negative SLE, in infants with congenital complete heart block, and in neonatal lupus.
- SS-B (La): positive in 10 – 15% of SLE and 10 – 15% Sjogren’s disease, also positive in antibody negative SLE and subacute SLE.
- Scl-70: positive in scleroderma and other connective tissue diseases.
- Jo-1: positive result for Jo 1 antibodies is consistent with the diagnosis of polymyositis and suggests an increased risk of pulmonary involvement with fibrosis in such patients.
For more information, see the section on Lupus.
ESR, WESTERGREN (blood)
Blood is placed in a long tube that is held vertically for one hour. The red cells will fall (or sediment). The height of the sedimented cells correlates with non-specific inflammation.
17β-Estradiol is the dominant form of estrogen in the human body. It is normally produced by the ovary, the adrenal gland (minor), and by peripheral conversion of adrenal androgens. It is measured to determine excessive estrogen in men and children. It is not as useful in determining reduced estrogen in women because the female reference range is very wide and reductions may remain in the normal range. Increased values are seen in children with: precocious puberty, estrogen producing tumours, and ingestion of exogenous estrogen. Male adults have increased values in estrogen producing tumours, gynecomastia, cirrhosis of the liver (metabolic breakdown imbalance), feminizing testes syndrome, estrogen medications, and spironolactone medication. Elevated values in female adults are difficult to distinguish from normal, and are found with estradiol-containing medications and pregnancy.
Decreased values are not generally detectable in children and male adults. In women, low values accompany ovarian failure, menopause, pituitary failure, and Turner’s syndrome.
FACTOR V LEIDEN AND PROTHROMBIN GENE MUTATIONS
Factor V Leiden is a major cause of unexplained thrombotic disease and is responsible for activated protein C (APC) resistance; a mutation in the prothrombin gene is an additional minor risk factor. These mutations can be rapidly detected using molecular methods.
FECAL FAT (stool)
Fat can be found in feces using a special stain and a microscope. Increased fat in feces indicates fat malabsorption.
FECAL MEAT FIBERS (stool)
Fecal meat fibers indicate incomplete digestion and absorption.
Ferritin is a test that indicates the level of stored iron. Low values indicate iron deficiency and high values are seen in both excess iron syndromes (hemochromatosis) and in inflammation of iron storage tissues (e.g. hepatitis). For more information, see the section on Hemachromatosis.
Fibrinogen is an important protein in the blood clotting mechanism. It is measure to determine the nature of bleeding disorders.
Folate (Folic acid and folinic acid) is a vitamin. Low levels are exceedingly rare as many foods are now fortified with folate. Low folate is due to extreme dietary deficiency and causes a particular form of anemia and skin disease. High levels are only seen with folate ingestion. High homocysteine may be due to relative folate deficiency. Folate deficiency has been implicated as a cause of neural tube defects in newborns.
FOLLICLE STIMULATING HORMONE (blood)
Follicle Stimulating Hormone (FSH) is a pituitary hormone that controls the maturation of “eggs” in the ovary and spermatozoa in the testes. Values rise in ovulation and ovarian or testicular failure (including menopause). It is low in infertility and pituitary insufficiency. Its level varies throughout a normal menstrual cycle.
GAMMA GLUTAMYL TRANSPEPTIDASE (blood)
Gamma Glutamyl Transpeptidase (GGT) is an enzyme found in the liver. Its values rise in liver disease and excessive alcohol consumption.
GLUCOSE (blood, urine)
Glucose is main form of circulating blood sugar. Its level is under the control of insulin. It is increased following meals and in diabetes. It may be low in response to meals (reactive hypoglycemia) or in excess insulin situations (too much insulin administration without food or an insulin-secreting tumor). Its main use is the diagnosis of diabetes or monitoring diabetic therapy. For more information, see the section on Diabetes.
GLUCOSE GESTATIONAL (blood)
Pregnant women are usually checked for the presence of Gestational Diabetes.
Screening for Gestational Diabetes
A 50 gram glucose drink is administered between the 24th and 28th week without regard to time of day or time of last meal. The serum glucose is measured 1 hour later. A high value of glucose indicates the need for a full diagnostic glucose tolerance test.
Full diagnostic Tolerance Test
A 100 gram glucose drink is administered in the morning after an overnight fast, and after at least 3 days of unrestricted diet and normal physical activity. Blood glucose is measured at 0, 1, 2, and 3 hours post-drink. For more information, see the section on Diabetes.
GLUCOSE TOLERANCE (blood)
The Glucose Tolerance test is the definitive test for diabetes mellitus. It is only carried out when this diagnosis cannot be made from single glucose measurements. It consists of taking a sugar drink followed by several blood glucose measurements. For more information, see the section on Diabetes.
The gram stain is the microscopic examination of a slide from a microbiology swab or a microbiology plate. A special stain is used. This study shows the presence of bacteria if they are present and categorizes them as gram positive (stain accepting) or gram negative. The test allows for a rapid initial assessment of bacterial infection.
GROUP B STREPTOCOCCUS (by REAL-TIME PCR)
Group B Streptococcus (GBS) is the leading cause of bacterial sepsis and meningitis for the last two decades. Screening during late pregnancy can help prevent neonatal infections. Real-time PCR allows rapid and sensitive detection of GBS.
Haptoglobin is a protein that “mops up” hemoglobin that is free (outside the red cells) in the serum. After binding hemoglobin it is removed from the serum. Low levels are found in red cell destruction (hemolytic anemia).
H. PYLORI BREATH TEST (breath)
The H. pylori breath test is used for the evaluation of gastritis and peptic ulcers. For more information, see the section on Helicobacter pylori.
HEMATOLOGY PANEL (blood)
The Hematology Panel (profile) is the mainstay of hematology diagnosis. For more information, see the sections on the Hematology Profile and Anemia.
Hemoglobin is a complex iron-containing protein that is responsible for carrying oxygen from the lungs to all the tissues of the body. It is measured as part of the Hematology Panel. Low hemoglobin is referred to as anemia: or more information, see the sections on the Hematology Profile and Anemia. High levels of hemoglobin (erythrocytosis) may be secondary (eg. hypoxia) or primary (eg. myeloproliferative disorder, or PRV).
HEMOGLOBIN A1c (blood)
Normal hemoglobin binds blood sugar (glucose) through an irreversible process known as glycosylation. The higher the glucose level, the greater the level of modified (glycated) hemoglobin. Because the life span of a red cell is about 120 days, the amount of glycated hemoglobin is a measure of the “average” blood glucose level over a four-month period. Its measurement is therefore recommended in all diabetics as a way of assessing diabetic control. For more information, see the section on Diabetes.
HEMOGLOBIN A2 (blood)
Hemoglobin A2 is one of the forms of Hemoglobin. It is measured to determine whether you have an abnormal type of hemoglobin (hemoglobinopathy) or an abnormal production of hemoglobin (thalassemia). For more information, see the section on Thalassemia.
HEMOGLOBIN, FETAL (blood)
Hemoglobin F is normally found in unborn babies and newborns. It is also present in adults with abnormal hemoglobin production.
When the plasma hemoglobin exceeds 5 g/L, the capacity of haptoglobin and hemopexin to “mop it up” may be exceeded and the free hemoglobin passes through the glomerulus and into the kidney tubule. Some hemoglobin enters the urine as free hemoglobin. The hemoglobin is absorbed by the proximal tubule and converted into hemosiderin. Hemosiderinuria occurs when the cells lining the proximal tubule are shed into the urine.
HEPATITIS A IGM (blood)
Hepatitis A IgM is the standard test for the presence of Hepatitis A infection. A positive test indicates that Hepatitis A infection has occurred in the past six months. A negative test indicates no infection from this agent in the past six months. For more information, see the section on Hepatitis.
HEPATITIS B CORE ANTIBODY (blood)
A positive Hepatitis B core antibody test indicates the presence of antibodies to a part of the Hepatitis B virus. It is present very early on in a Hepatitis B infection and may stay positive for decades after the infection has resolved. Immunization does not produce positive results. Thus, a positive does not diagnose Hepatitis B; the Hepatitis B antigen test must be done to diagnose the presence of infection. For more information, see the section on Hepatitis.
HEPATITIS B SURFACE ANTIBODY (blood)
A positive Hepatitis B surface antibody test indicates that an individual has either been immunized with Hepatitis B vaccine or has encountered the actual Hepatitis B virus. For more information, see the section on Hepatitis.
HEPATITIS B SURFACE ANTIGEN (blood)
The test for Hepatitis B surface antigen tells whether the Hepatitis B virus is present. A positive test is found in active Hepatitis B infection, in chronic Hepatitis B, and in the Hepatitis B carrier state. For more information, please see the section on Hepatitis.
HEMOGLOBIN ELECTROPHORESIS (blood)
Hemoglobin electrophoresis was the main test to detect the presence of abnormal hemoglobin formation. Today, we do this study using High Pressure Liquid Chromatography but the name “electrophoresis” is still commonly used. For more information, please see the section on Thalassemia.
HLA B27 (blood)
HLA B27 is strongly associated with ankylosing spondylitis and several other rheumatic diseases. Molecular methods allow specific and sensitive detection of most subtypes of the HLA B27 allele.
The level of homocyst(e)ine has been shown to be a risk factor for vascular disease and thromboembolism. For more information, see the section on Homocysteine.
HUMAN CHORIONIC GONADOTROPIN (blood, urine)
Human Chorionic Gonadotropin (hCG) is a hormone produced by a pregnancy (chorion layer of the placenta) as a way to nurture the pregnancy in the first few months. It is present in the maternal blood on the first day the pregnancy is established. It moves quickly from the blood into the urine. The qualitative (i.e. ‘positive’ or ‘negative’) detection of hCG is the basis of urine pregnancy tests. Quantitative (i.e. numerical) measurements of hCG are used to diagnose pregnancy as well as reveal problems such as ectopic pregnancy or hydatidiform mole, spontaneous abortion, or tumors such as choriocarcinoma of the ovary or testes. HCG is also part of the Triple Marker Test. For more information, see the section on the Pregnancy.
HUMAN GROWTH HORMONE (blood)
Human Growth Hormone (GH) is produced by the pituitary gland. It stimulates the growth of bones. Too much causes gigantism and acromegaly, while too little results in dwarfism.
HUMAN PAPILLOMAVIRUS (HPV)
HPV, or human papillomavirus, is the most common sexually transmitted infection in the world. There are more than 100 different types of HPV that may cause a variety of diseases ranging from warts to cancer. Cervical cancer is strongly associated with high-risk HPV infection. Identifying the virus can shed light on the cause of abnormal cells seen during a Pap test and help identify patients who may require further tests. A positive result for any of the high-risk types can be closely monitored for any pre-cancerous conditions. A negative test for high-risk HPV can provide peace of mind that the patient is at lower risk for developing cervical cancer.
5-HYDROXYINDOLEACETIC ACID (urine)
5-HIAA is produced in excess and can be measured in the urine by an unusual tumor of the intestine known as a carcinoid. The presence of a carcinoid tumor may cause symptoms of hot flushes, hypertension and a tricuspid valve heart murmur.
IMMUNOGLOBULIN A (blood)
Immunoglobulin A (IgA) is a type of antibody that is found on mucous membranes, (e.g. gastrointestinal tract, vagina). If deficient, patients may suffer from chronic diarrhea and certain types of recurrent infections. For more information, see the section on Multiple Myeloma.
IMMUNOGLOBULIN E (blood)
Immunoglobulin E (IgE) is a type of antibody that mediates the allergic reaction. It is normally very useful in removing unwanted materials from the body. In allergic persons the level may be abnormally high. Thus, it can be used to tell if a condition is allergic in nature. It does not reveal to what a person may be allergic. For this purpose, the Specific Allergen IgE (SAIGE) test is used. For more information, see the section on Allergies.
IMMUNOGLOBULIN G (blood)
Immunoglobulin G (IgG) molecules are the main type of antibodies that circulate in the blood stream. General increases in IgG accompany infections and inflammation and malignancy of the antibody producing cells. Decreases occur in some infections and may also be due to a genetic or acquired defect. When the IgG is low a person may be susceptible to infections. For more information, see the section on Multiple Myeloma.
IMMUNOGLOBULIN M (blood)
Immunoglobulin M (IgM) molecules are antibodies that are recently formed and appear early in infections. Increased values are seen in: acute stimulation of the immune system (immunization, viral infections), selective increase is seen in neoplasia, IgM myeloma, and Waldenstrom’s macroglobulinemia. Decreased values are seen in: children, agammaglobulinemia (inherited) and myeloma. For more information, see the section on Multiple Myeloma.
IMMUNOFIXATION (blood, urine)
Immunofixation is a chemical method for identifying abnormal proteins in serum and urine. It is used in the diagnosis and monitoring of multiple myeloma or monoclonal gammopathy of uncertain significance (MGUS). For more information, see the section on Multiple Myeloma.
The International Normalized Ratio (also known as the Prothrombin Time) measures defects in part of the clotting mechanism. It is used to detect clotting abnormalities. However, it is mainly used to measure the effect of “blood thinning” medications such as Warfarin or Coumadin. For more information, please see the section on Anticoagulant Monitoring.
Measuring insulin is useful in diagnosing insulinoma, when used in conjunction with proinsulin and C-peptide measurements. It is not part of the initial diagnostic work-up of diabetes.
Iron is an essential nutrient required for normal hemoglobin formation. Inadequate iron may lead to iron deficiency anemia. The test is used to measure iron stores although the Serum Ferritin test is the recommended initial test for assessment of iron disorders.
JOINT FLUID CRYSTAL
The diagnosis of the cause of a swollen joint may be enhanced by removing some of the joint fluid and examining it under a microscope. Gout is characterized by the presence of uric acid crystals.
JOINT FLUID DIFFERENTIAL
The cells in a joint fluid are examined to determine the cause of a joint swelling.
JOINT FLUID, PROTEIN
The amount of protein in a joint fluid helps to determine the cause of the swelling.
The KOH test is used to identify fungus infections of the skin.
LACTATE DEHYDROGENASE (blood)
Lactate Dehydrogenase (LDH, LD) is an enzyme found in any cell that metabolized glucose, and so is present in most tissues. An increase in the LD commonly indicates inflammation in the liver or muscle or destruction of red cells.
Lead poisoning is generally due to chronic overexposure in industry or in children with pica (compulsive eating of non-foods). The overt syndrome involves GI symptoms, convulsions, coma, abdominal pain, neuropathy, anemia, and nephropathy. Chronic exposure may cause decreased mental functioning without ever causing the overt syndrome. While it is recommended that values in children should not exceed 0.48 umol/L, a study in a Vancouver population found it unusual for local children to exhibit a blood lead level greater than 0.25 umol/L.
LEUCOCYTE ALKALINE PHOSPHATASE (blood)
Leucocyte Alkaline Phosphatase is present in the granules of neutrophils. The amount can be measured as the LAP score. Stimulated neutrophils have higher concentrations. LAP is decreased in CML and the LAP score has been used to distinguish CML from reactive neutrophilia and other myeloproliferative syndromes. Increased values are seen in neutrophil response to infection, inflammation, tumor, necrosis; polycythemia, and essential thrombocythemia. Decreased values are seen in chronic myelogenous leukemia (CML), some myelodysplastic syndromes, acute myelogenous leukemia (AML), paroxysmal nocturnal hemoglobinuria (PNH), idiopathic thrombocytopenic purpura (ITP), pernicious anemia, and infectious mononucleosis. However, the LAP score is now considered an obsolete test: more specific molecular tests are done in suspected cases of myeloproliferative disorders using peripheral blood.
LUTEINIZING HORMONE (blood)
Luteinizing Hormone (LH) is made by the pituitary gland. It controls the production of Estrogen in the ovary and Testosterone from the testes. It is elevated in ovarian failure (menopause) or testicular failure. It is low in pituitary insufficiency.
Lipase is an enzyme produced by the pancreas to facilitate fat digestion. It is elevated in pancreatitis, an inflammation of the pancreas causing severe abdominal pain.
Lithium is a drug that is used for the treatment of manic-depressive (bipolar) disorders. Effective medication with Lithium is adjusted by measuring its level in serum. For more information, see the section on Therapeutic Drug Monitoring.
Reference Range update
MAGNESIUM (blood, urine)
Magnesium is an element that is necessary for many metabolic functions (an enzyme co-factor). Its reduction may occur in gastrointestinal and nutritional disorders.
Measuring urine magnesium is probably the best way to determine magnesium status, but only when performed as part of a loading test.
Malaria is a parasitic infection of the red cells that is transmitted by mosquitoes commonly found in equatorial countries. It is diagnosed by careful examination of the blood with a microscope. The chances of finding malarial parasites in blood are high if blood is taken during febrile episodes, but a negative test does not exclude malaria, especially in patients with history of travel to malarial zones. Note that malaria is no longer just a tropical disease: it is becoming increasingly common in Canada due to world-wide travel and malarial resistance to some anti-malarial drugs.
MERCURY (blood, urine)
Metallic mercury (Hg) is essentially nontoxic, and may be consumed orally without significant side effects. Inhaled Hg vapor, however, can lead to both chronic and acute intoxications through chemical modification to the ionized (Hg2+) species. Further conversion to methyl mercury results in a high toxic species with a preference for fatty tissues and nerve cells. Small amounts of mercury are released from dental amalgams but this level of exposure is not considered significant. The most significant source of mercury exposure for most persons is seafood, especially with larger predatory fish (e.g. tuna, swordfish) or long-lived species (e.g. rock cod).
A rare tumor of the adrenal gland (pheochromocytoma) may secrete compounds such as adrenaline which cause severe hypertension. ‘Metanephrines’ refer to adrenaline and nonadrenaline metabolites: these can be detected in the urine, where they provide a convenient screening test for pheochromocytoma. For more information, see the section on Adrenal Disease.
METHICILLIN-RESISTANT STAPHYLOCOCCUS AUREUS (by PCR)
S. aureus is a microorganism that may acquire resistance to a class of antibiotics and detection of this is important for infection control. Molecular methods allow rapid and simultaneous identification of Staphylococcus aureus and the genes associated with antibiotic resistance and virulence. This assay also identifies those strains likely to be associated with the community-acquired variants of MRSA.
Despite its name, Microalbumin is not “small albumin” but rather normal albumin present at low levels in the urine. It is an important test to be carried out periodically in all diabetics in order to detect the early signs of kidney disease. In order to compensate for the variable concentration of urine, Microalbumin is usually reported as a ratio to urine creatinine, or the ‘Albumin-Creatinine Ratio’ (ACR). For more information, see the section on Diabetes.
MONO TEST (blood)
The mono test is important for diagnosis of infectious mononucleosis. For more information, see the section on Infectious Mononucleosis.
The blood morphology examination is done by examining a smear of blood on a glass slide using a microscope. It is done when results of the Hematology Panel (Profile) are abnormal, and more clearly identifies the nature of the abnormality. For more information, see the section on the Hematology Profile.
OCCULT BLOOD (stool)
Occult blood means unseen blood. It is a test carried out on feces as a way of detecting the presence of a bowel lesion such as cancer of the colon. For more information, see the section on Colon Cancer.
OVA & PARASITE (stool)
The O&P test is carried out by examining feces (stool samples) looking for worms or other abnormal organisms that may be the cause of diarrhea or malabsorption.
Olanzapine (Zyprexa®) is an anti-psychotic drug. Measurement is carried out to adjust the dosage. For more information, see the section on Therapeutic Drug Monitoring.
Oxalate is a metabolic end product that is excreted into the urine. High levels may cause calcium oxalate stones to form. Causes of increased oxalate include diet (e.g. animal protein, purines, gelatin, calcium, strawberries, pepper, rhubarb, beans, beets, spinach, tomatoes, chocolate, cocoa, tea), intestinal disease and rare inborn errors of metabolism.
PATERNITY TESTING (blood)
Resolution of paternity and other biological relationships can be achieved using DNA methods. PCR-based testing provides rapid and accurate genetic fingerprints of individuals. These results can be compared between child and alleged father in order to determine the likelihood of paternity. The method is also applicable to other relationships in question, such as maternity or sib-ship. There is a fee for this service – please refer to the appropriate section of this website for more information or call 1-800-663-9422 ext. 4535. For more information on paternity testing at LifeLabs, please click here.
Phenobarbital is a drug used for the treatment of seizure disorders. Adjustment of the appropriate dosage is made by measuring the drug in serum. For more information, see the section on Therapeutic Drug Monitoring.
Phenytoin is an anticonvulsant drug. Adjustment of the appropriate dosage is made by measuring the drug in serum. For more information, see the section on Therapeutic Drug Monitoring.
PHOSPHORUS, INORGANIC (blood, urine)
Phosphorus is an essential element needed in every cell. It is closely linked to calcium metabolism. Phosphorus is present in the body in two basic forms: (1) bound to organic molecules (such as ATP) where it often serves to provide energy transfer, and (2) in a free (ionic) form as phosphate ion (PO4). This latter group is referred to as the inorganic phosphorus (or phosphate). Inorganic phosphate is closely associated with acid-base balance, calcium metabolism, and glucose flux into cells. Increased values are seen in: compensation for primary hypocalcemia (hypoparathyroid), hypercalcemia of rapid bone resorption, renal disease. Decreased values are seen in: compensation for primary hypercalcemia (1° hyperparathyroidism), post-glucose ingestion or insulin administration, and Fanconi’s syndrome of the proximal tubule.
Urine phosphorus is measured as a secondary test to understand calcium metabolism.
Pinworms are tiny, almost microscopic worms, which infect the anal area and cause itching. They can be identified under a microscope. The collection of the sample is done using tape fixed to a microscope slide.
PLATELET COUNT (blood)
Platelets are tiny cells found in the blood stream. They have the ability to stick together and form tiny “plugs” in any damage to blood vessels. Thus, they are necessary to stop bleeding. Low levels of platelets indicate a bleeding or bruising tendency. High levels may be associated with unwanted blood clot formation or bleeding. Platelets may be normal in amount but may sometimes function abnormally. This problem requires special tests to diagnose.
PORPHYRINS (blood, urine, feces)
A group of inherited disorders of hemoglobin metabolism are called porphyrias. They result in a spectrum of syndromes from mental derangement, light sensitive skin disease, and acute abdominal pain. These disorders can be diagnosed by measuring porphyrins in the blood, serum, urine, and feces, though the recommended first-tier test is urine porphobilinogen.
POTASSIUM (blood, urine)
Potassium is an important element that is necessary for proper cell membrane activity. Too much potassium causes cells to “twitch” inappropriately and if high enough may cause the heart to go into an arrhythmia. Common causes are renal failure, hemolysis, adrenal insufficiency, acidosis, dehydration and drugs. Low potassium may cause muscle weakness and paralysis. Decreased values are seen with prolonged vomiting/diarrhea, hyperaldosteronism and drugs.
The urine potassium level indicates the level of potassium in the diet (as long as the serum level is normal).
PREGNANCY TEST (blood, urine)
The pregnancy test detects the presence of Chorionic Gonadotropin in serum or urine. It is turned positive by pregnancy, tumors, or (rarely) unusual antibodies in the serum. The serum test is typically positive within 8-10 days of conception in most women, while the urine test may be unreliable prior to the first week following the first missed menstrual period. Sometimes a pregnancy occurs but is “lost”, though the test may stay positive for some days. For more information, see the section on Pregnancy.
Progesterone is normally present at low levels in women. It rises during the latter third of the menstrual cycle if ovulation has occurred.
PROGESTERONE, 17OH (blood)
17OH Progesterone is made by the adrenal gland. It is raised if there is an internal malfunction of adrenal metabolism. In such cases, the adrenal may manufacture excessive androgens. Thus, the test is used to investigate hirsutism (excessive body hair in women), as well as suspected congenital adrenal hyperplasia.
Prolactin is a pituitary hormone whose purpose is to mediate lactation following delivery. It is elevated in certain tumors of the pituitary gland in both men and women. Increased values are seen in: pregnancy and lactation, prolactin secreting adenomas (values over 6000 are almost always prolactinomas), non-functional tumours of the hypothalamus, empty sella syndrome and certain drugs ( neuroleptics: fluphenazine, haloperidol; anti-emetics: metoclopramide, domperidone; antidepressants: imipramine, amitriptyline, and methyldopa, opiates, estrogens, cimetidine). Miscellaneous causes include: renal disease, surgical stress, sleep, exercise, sexual intercourse, hypoglycemia, post epileptic siezure, breast stimulation and chest lesions, primary hypothyroidism, cirrhosis, and spinal cord disease. Reduced values have no clinical significance but may be caused by bromocriptine.
PROTEIN ELECTROPHORESIS (blood, urine)
Protein electrophoresis is a chemical technique used to identify abnormal proteins, particularly monoclonal immunoglobulins. For more information, see the section on Multiple Myeloma.
PROTEIN, TOTAL (blood, urine)
Total protein measurements determine the amount of all the proteins in serum or urine. This test is used in conjunction with measurements of albumin or with protein electrophoresis to study deficiencies or over- production of serum protein production. Normally, very little protein is present in urine: high amounts may indicate kidney disease.
PROTHROMBIN TIME (blood)
The International Normalized Ratio (also known as the Prothrombin Time) measures defects in part of the clotting mechanism. It is used to detect clotting abnormalities. However, it is mainly used to measure the effect of “blood thinning” medications such as Warfarin our Coumadin. For more information, see the section on Anticoagulant Monitoring.
PROSTATE-SPECIFIC ANTIGEN (blood)
The Prostate Specific Antigen (PSA) is used to detect the presence of prostatic carcinoma or to monitor the effect of therapy. It is not recommended as a screening test, though it may be performed as such on a patient-pay basis. For more information, see the section on Prostate Cancer.
PARATHYROID HORMONE (blood)
Parathyroid hormone (PTH) is the main control of calcium in the serum. It is measured to determine why the calcium level is abnormal.
PARTIAL THROMBOPLASTIN TIME (blood)
The activated Partial Thromboplastin Time is a test of the clotting mechanism of the blood. It is used in the diagnosis of bleeding disorders. If abnormal (prolonged), further testing is warranted to identify the specific disorder.
In the inherited disorder known as Acute Intermittent Porphyria patients suffer excruciating abdominal pain and produce excessive amounts of porphobilinogen in their urine.
RHEUMATOID FACTOR (blood)
The Rheumatoid Arthritis test (or Rheumatoid Factor = RF) is used to diagnose Rheumatoid arthritis. For more information, see the section on Rheumatoid Arthritis.
Renin is an enzyme hormone produced by the kidney that controls blood pressure. It should not be confused with rennin that is an enzyme found in milk. Excessive production of renin (certain kidney disease, blood vessel blockage, and extraordinarily rare tumors) will cause a form of high blood pressure. However, it is measured most often to check for suppression by high levels of aldosterone or other mineralocorticoids.
RETICULOCYTE COUNT (blood)
Reticulocytes are newborn red cells. An increased number of reticulocytes in blood indicates that red cells are being formed faster than normal, eg. in response to blood loss or hemolysis. Decreased levels may be seen in nutritional deficiencies or bone marrow failure.
RH FACTOR (blood)
All red cells have a “type” (A, B, AB, and O) and also may be classified as Rh+ or Rh-. Knowing this is important for pregnant women since Rh- women may develop antibodies that can harm a Rh+ baby unless prophylaxis is undertaken.
When a bacterial infection is considered, the potentially infected area is swabbed and the swab sent to the lab. The lab then grows any bacteria that are present, determines whether they are harmful (pathogenic), and determines the antibiotics that will treat the infection most effectively.
SEMEN EXAMINATION (semen)
Semen is examined as part of an infertility work-up. The sample is examined for the presence of spermatozoa, how many are present (the count), the number of abnormal forms present, and whether they move quickly or not (motility). To be performed properly the sample must be examined fresh i.e. within 2 hrs of collection. Semen is also examined following a vasectomy to determine whether it is “complete” or not. In this case, only the presence or absence of sperm is noted (and if present, a count is made).
SICKLE CELL TEST (blood)
Sickle cell anemia is a condition that mainly affects people of African descent. The red cells in this disorder “crumple up” if the oxygen level becomes too low. The cells, under a microscope, become sickle shaped (rather than being “biconcave discs” or dimpled spheres). Sickle Cell Test is a qualitative solubility test for the presence of sickling hemoglobin in human blood.
SODIUM (blood, urine)
Sodium is the major ion in the serum. Abnormalities in sodium concentration cause blood pressure abnormalities and edema and may be due to hormonal or to kidney disease. Increased values are seen in dehydration, IV fluids administration, posterior pituitary disease, adrenal disease, and kidney disease. Decreased values are called hyponatremia and are seen in over-hydration, renal disorders, cardiac failure, pituitary and adrenal disorders, and excessive glucose or lipids.
Urine sodium is often used to evaluate the level of salt in the diet.
THYROXINE, FREE (blood)
Thyroxine (T4) is the main thyroid hormone. It is raised in hyperthyroidism and low in hypothyroidism. Free thyroxine (FT4) refers to the miniscule active fraction of total T4 which is available to the body. For more information, see the section on Thyroid Function Tests.
Testosterone is the main male hormone. In men, low testosterone causes impotence. In women, elevated testosterone causes hirsutism (excess hair) or even virilization (in cancers). Low testosterone may also be the cause of loss of libido. The measurement may be confused by alterations of Sex Hormone Binding Globulin (SHBG), which binds a considerable fraction of available testosterone.
TESTOSTERONE, FREE (blood)
Free testosterone is a special test that directly measures the level of circulating free (unbound) testosterone. It cannot be requested simultaneously with Bioavailable Testosterone.
TESTOSTERONE, BIOAVAILABLE (blood)
Bioavailable testosterone (BAT) refers to the estimation of circulating testosterone that is available to the body. This requires the measurement of total testosterone, sex hormone binding globulin (SHBG) and albumin. Specifically, BAT is taken as testosterone not bound to SHBG. Using these results, it is also possible to calculate the level of free testosterone (cFT), which compares very well with free testosterone values obtained through high-level reference methods.
THALASSAEMIA INVESTIGATION (blood)
Thalassemia is the abnormal production of otherwise normal hemoglobin molecules. It is covered in more detail in another section. For more information, see the section on Thalassemia.
Theophylline is an asthma drug. It can be measured to enhance the dosage regime. For more information, see the section on Therapeutic Drug Monitoring.
THROMBIN TIME (blood)
The Thrombin Time is a test of the clotting mechanism of the blood. It is employed in work-ups of blood coagulation disorders.
Thyroglobulin is a protein found inside the thyroid gland that helps to store thyroid hormone until it is needed. It is not normally released into the serum, but may be detected with certain thyroid cancers and is used to monitor the success of therapy of these conditions.
THYROGLOBULIN ANTIBODIES (blood)
Thyroglobulin antibodies are sometimes increased in thyroid inflammation (Thyroiditis). They are also measured to ensure that Thyroglobulin results are not falsely decreased (or, less commonly, increased) due to interference. For more information, see the section on Thyroid Function Tests.
THYROID PEROXIDASE ANTIBODIES (blood)
Antibodies to the thyroid peroxidase enzyme TPO (formerly known as anti-microsomal antibodies) are antibodies to thyroid tissue. They are often present at low levels in healthy people, while high levels indicate thyroid disorders such as thyroiditis. For more information, see the section on Thyroid Function Tests.
TOTAL IRON BINDING CAPACITY (blood)
Iron is an essential element that is transported in the plasma (i.e. non-red cell fraction of blood) almost exclusively by the protein rransferrin (see below). The total iron binding capacity (TIBC) is a measure of the total level of iron that can be bound by serum proteins. As the TIBC level is very similar to that of transferrin, the two are usually considered to be interchangeable. Measurements of TIBC are used as a secondary test of iron metabolism (ferritin is the primary test) in conjunction with serum iron. These results are used to calculate the percentage saturation of serum protein iron binding sites, which is used to evaluate iron status (deficiency and overload). See also: Transferrin. For more information, see the section on Hemachromatosis.
Transferrin is a key protein involved in iron transport throughout the body. Measurements of its level are used as a secondary test of iron metabolism (ferritin is the primary test) in conjunction with serum iron. These results are used to calculate the percentage saturation of transferrin’s iron binding sites, which is used to evaluate iron status (deficiency and overload). See also: Total Iron Binding Capacity. For more information, see the section on Hemachromatosis.
TRICHOMONAS WET MOUNT
Trichomonas is a microorganism that infects the genital region. It is detected by collecting a drop of fluid and examining it under a microscope.
Triglycerides are fats that circulate in the blood stream. Their measurement helps provide a profile of the blood fat (lipid) content and is used to calculate levels of LDL (“bad cholesterol”). For more information, see the section on Cholesterol.
THYROID STIMULATING HORMONE (blood)
Thyroid Stimulating Hormone (TSH) is produced by the pituitary gland and it controls the thyroid gland. It is the main thyroid function test: values rise in hypothyroidism and decline in hyperthyroidism. TSH levels are slow to respond to changes in thyroid functions (typically over a period of weeks), but they show a more pronounced change than is seen for free T4. For more information, see the section on Thyroid Function Tests.
UREA (blood, urine)
Urea is a waste product of protein metabolism. It is removed from the body by the kidney. Its measurement is used as a test of kidney function because when the kidney is impaired, levels of urea go up. It is also known as the BUN (blood urea nitrogen).
URIC ACID (blood, urine)
Uric acid is a waste product of nucleic acid (DNA, RNA) metabolism. It is elevated in gout, kidney disease and in conditions where body tissues degenerate rapidly. A high urine uric acid is a risk factor for uric acid stone formation.
Macroscopic urinalysis is a common screening test where a urine sample is tested for several chemical substances (glucose, protein, blood, etc.). If results are abnormal, the sample may then be examined under a microscope (see Urinalysis, microscopic). For more information, see the section on Urinalysis.
Microscopic urinalysis consists of examining urine under a microscope to look primarily for red blood cells, white blood cells and degraded cell deposits from the walls of the urinary tract (casts). This information is used to help diagnose urinary tract infection (UTI) and other disorders of the kidney. For more information, see the section on Urinalysis.
Usually detected as part of routine urinalysis. For more information, see the section on Urinalysis.
Obstruction to bile flow
Negative if complete
Decreased early, increased late
Decreased early, increased late
VALPROIC ACID (blood)
An anti-epileptic drug. Serum measurements help with dosage adjustment. For more information, see the section on Therapeutic Drug Monitoring.
VANILLYLMANDELIC ACID (blood)
Vanillylmandelic acid (VMA) is a catecholamine metabolite. Levels in urine are used as a screening test for the rare tumour pheochromocytoma, though current guidelines recommend urine metanephrines for this purpose. For more information, see the section on Adrenal Disease.
In certain conditions (macroglobulinemia, myeloma) the blood becomes thick and sluggish. Viscosity measurements quantitate this abnormality.
VITAMIN B12 (blood)
Vitamin B12 deficiency may lead to macrocytic anemia and to neurological degeneration of part of the spinal cord.
VITAMIN D (blood)
Vitamin D status is measured as the total level of its 25-hydroxy vitamin D (25-OH Vit D) metabolites 25-OH Vit D3, derived endogenously from sunlight, and 25-OH Vit D2 obtained from supplementation. Serum levels decrease with age and pregnancy and vary with sun exposure and supplementation; values tend to be highest in late summer and lowest in spring. Severe deficiency manifests as rickets in children and osteomalacia in adults and is characterized by decreased serum calcium and phosphorus and increased alkaline phosphatase. Vitamin D intoxication caused by extremely large doses (50,000 – 100,000 IU/day: for comparison, Health Canada recommends no more than 2000 IU/day from all sources) is more common in infants and children than adults and results in hypercalcemia, increased risk of renal stones, soft-tissue calcification, gastrointestinal symptoms, and growth and mental retardation. Note that extremely high levels may be observed in hypoparathyroid patients receiving physiological doses of Vitamin D.
LifeLabs measures both 25-OH Vitamin D3 and 25-OH Vit D2 and reports the sum of their concentrations, as their physiological activities are considered to be equal. Optimum levels are still a matter of debate, but there is agreement that levels below 50 nmol/L are insufficient and those above 200 nmol/L are toxic.
1,25-Dihydroxy Vitamin D3 (1,25-OH2 Vit D), the principal active form of Vit D, is formed by renal cells and reflects calcium synthesis by the body. Secretion is influenced by parathyroid hormone (PTH) and the calcium and phosphorus content of the diet. The main reasons for measuring 1,25-OH2 Vit D are to differentiate primary hyperparathyroidism from hypercalcemia of cancer, distinguish between Vit D-dependent and Vit D-resistant rickets, monitor the Vit D status of patients with chronic renal failure, and assess compliance of 1,25-OH2 Vit D therapy. It is often useful to measure PTH in conjunction with 1,25-OH2 Vit D.
Testing for 1,25-OH2 Vit D is typically indicated only for monitoring 1,25-OH2 Vit D therapy or determining Vit D status in patients with significant renal disease. For all other clinical situations, Vit D status is best measured via 25-OH Vit D.
Vitamin D update
VANCOMYCIN-RESISTANT ENTEROCOCCI (by PCR)
Vancomycin-resistant enterococci (VRE) are a class of antibiotic-resistant microorganisms. They have emerged as an important cause of nosocomial infections. The molecular method allows rapid and simultaneous identification of major VRE variants: Enterococcus faecalis, E. faecium, E. gallinarum, E. casseliflavus and E. flavescens.
White Blood Cell count is part of the routine Hematology Panel.
Whipple’s Disease is a systemic infection characterized by fever, weight loss, diarrhea, polyarthritis and adenopathy. The causative organism is very difficult to culture; however, molecular methods can detect its presence in peripheral blood samples. The ideal sample is tissue biopsy, so negative results from peripheral blood do not rule out infection.
Yeast, such as Candida albicans can cause infections of the mouth or genitalia. The microbiology lab can detect the presence of yeast. Although there is much non-medical information about yeast in the blood, this is something that only occurs in rare situations (patients who are gravely ill).
YERSINIA (by PCR)
Yersinia species are among the many microorganisms that cause diarrhea and other gastrointestinal symptoms. The molecular method allows rapid and simultaneous detection of major pathogenic Yersinia species.
ZINC (blood, urine)
Zinc is not very toxic. However, true zinc deficiency may lead to the failure of wounds to heal properly.