Anemia is a condition that develops when your red blood cell count or hemoglobin is less than normal.
The condition is often associated with being tired and weak. The reason for this is that anemia occurs when your body doesn't have adequate healthy red blood cells. Red blood cells carry oxygen to the body's tissues.
There are different types of anemia, including, but not limited to:
Iron-deficiency anemia, which is the most common type of anemia and occurs when your blood doesn't have enough iron to produce healthy red blood cells and hemoglobin.
The World Health Organization (WHO) states that this type of anemia, which is the most common and widespread nutritional disorder in the world, largely contributes to the fact that more than 30 percent of the world's population is anemic. (9)
Red blood cells carry oxygen to the body's tissues and remove carbon dioxide. Not having enough working red blood cells may lead to tiredness and shortness of breath.
Aplastic anemia is a blood disorder in which the body's bone marrow — the soft tissue in the center of bones — doesn't make enough healthy blood cells. Because of this, it is sometimes referred to as bone marrow failure.
While the condition is rare, each year between 600 and 900 people in the United States are diagnosed with aplastic anemia, according to the Aplastic Anemia and MDS International Foundation, although the accuracy of the epidemiological data for the United States is still being determined. (3) In Western countries, the incidence is approximately two per million per year, and estimated to be two- to threefold higher in Asia. (21)
The disorder affects men and women equally, and most commonly develops in adults between ages 20 and 25, as well as those over 60, according to the National Institute of Diabetes and Digestive and Kidney Diseases. (4)
Sickle cell anemia is an inherited blood disorder characterized by both a deficiency of healthy red blood cells and painful episodes called sickle cell crises.
The disorder is caused by a mutation in the gene that tells the body to make hemoglobin, a protein found in red blood cells that binds to oxygen in the lungs and carries it to tissues throughout the body.
As a result of the mutation, the body produces a defective form of hemoglobin called hemoglobin S, which causes red blood cells to sickle, or develop a crescent shape.
Sickle cells are stiff and sticky and tend to block blood flow in the vessels of the limbs and organs, causing pain and raising the risk for infection.
Sickle cells also have a shorter life span than normal red blood cells, leading to an overall shortage of red blood cells and, consequently, anemia.
Pernicious anemia refers to vitamin B12 deficiency caused by autoantibodies that interfere with vitamin B12 absorption by targeting intrinsic factor (IF), gastric parietal cells, or both. This type of anemia occurs when your body cannot absorb vitamin B12, which is needed to make healthy red blood cells and to keep the nervous system working properly. (14,22)
The condition can run in families and is an autoimmune condition. B12 deficiency from low intake can also mimic pernicious anemia as they both result in anemia from reduced available B12 for red blood cell creation. (14)
At the time it was described, PA was associated with continuous worsening of symptoms and even death without an available treatment. (22)
With proper treatment, people who have pernicious anemia can recover, feel well, and live normal lives.
Anemia of chronic disease is also sometimes called anemia of chronic inflammation or anemia of inflammation.
Anemia of inflammation and chronic disease is considered the second most common form of anemia after iron-deficiency anemia. (12) But the exact incidence of chronic disease anemia is not known, possibly because it's underreported and often goes unrecognized.
This type of anemia occurs when a long-term medical condition affects your body's ability to produce healthy red blood cells. Underlying conditions can vary and may include chronic illnesses such as cancer, infections, kidney disease, and autoimmune and inflammatory diseases like rheumatoid arthritis or lupus. Most often, the chronic disease prevents your body from effectively using iron to create new red blood cells, even if there are normal or high levels of iron stored in the body. Treatment for certain diseases can also affect red blood cell production. (12,13)
Signs and Symptoms of Anemia
Depending on the type of anemia you have, you may experience a variety of symptoms. The most common symptom of all anemias is weakness. Here are some other symptoms.
Iron deficiency anemia symptoms may be mild, but as the condition advances, can get worse and include: (11)
- Extreme fatigue
- Pale skin
- Chest pain, rapid heartbeat, or shortness of breath
- Headache, dizziness, or light-headedness
- Cold hands and feet
- An inflamed or sore tongue
- Brittle nails
- Odd cravings for ice, dirt, or starch
- Loss of appetite, most often in babies and kids
- Skin rashes
These symptoms may be severe from the start, or gradually worsen over time.
Other symptoms include:
- Shortness of breath and chest pain
- Dizziness, especially after standing up from a sitting or lying position
- Pale skin
- Bruising or bleeding easily
- Uncontrollable bleeding
- Nosebleeds, bleeding gums, bloody stool, or heavy menstrual bleeding
- Cold feeling in your hands and feet
- Fever due to infection
- Recurring infections or flu-like symptoms
- The appearance of small red dots on the skin that indicates bleeding under the skin
- Rapid heart rate
Sickle cell anemia symptoms can develop in some children earlier than others and typically start after the fifth or sixth month of life. Common signs and symptoms include: (8)
- Yellowish skin, known as jaundice
- Yellowish whites of the eyes, known as icterus
- Fatigue or fussiness
- Painful swelling of the hands and feet
- Frequent infections, especially pneumonia
- Fatigue and weakness
- Episodes of pain, called sickle cell crises, occur when sickled red blood cells block blood flow to the limbs and organs
Pernicious anemia may show similar symptoms to other anemias. But because it is caused by lack of absorption of vitamin B12, and similar to inadequate B12 intake in the diet, a severe deficiency in B12 may cause: (14)
- Tingling and numbness in hands and feet
- Muscle weakness
- Loss of reflexes
- Loss of balance
- Trouble walking
- Weakened bones, leading to hip fractures
- Neurological problems, such as confusion, dementia, depression, and memory loss
- Nausea, vomiting, heartburn, abdominal bloating and gas, constipation or diarrhea, loss of appetite, and weight loss
- Enlarged liver
- Smooth, thick, red tongue
Infants who have B12 deficiency may show the following signs and symptoms: (14)
- Poor reflexes or unusual movements like face tremors
- Difficulty feeding due to tongue and throat problems
- Permanent growth problems if left untreated
Anemia of chronic disease may cause similar signs and symptoms to other anemias, such as fatigue, pale skin, light-headedness, shortness of breath, rapid heartbeat, irritability, and chest pain. (12)
Causes and Risk Factors of Anemia
Red blood cells play a central role in anemia.
While white blood cells fight infection and platelets help your blood clot, red blood cells carry oxygen throughout your body.
Hemoglobin is an iron-rich protein that's found in red blood cells. Hemoglobin is what makes it possible for red blood cells to take oxygen from your lungs and carry it to places throughout your body. Hemoglobin also takes carbon dioxide from different areas of your body and brings it to your lungs so your lungs can get rid of it when you exhale.
Your bone marrow, which is in your large bones, produces red blood cells. But the vitamin B12, folate, and other nutrients that we get from food are needed to produce hemoglobin and red blood cells.
In addition to not having enough red blood cells, you can also become anemic if your body gets rid of red blood cells, or if, when you bleed, your body loses red blood cells more quickly than they can be replaced. (2)
Each type of anemia is caused by something different, and each ranges from mild to severe.
Iron-deficiency anemia develops when your body doesn't have enough iron because of blood loss, consuming inadequate amounts of iron, or having a medical condition that affects your body's ability to absorb iron from the gastrointestinal tract. (10)
Aplastic anemia is thought to be either "acquired" or "inherited," though the exact cause is not known.
Acquired aplastic anemia, which is more common than the inherited form, may result from:
- Toxins, including benzene (a chemical sometimes used in manufacturing and chemical synthesis), pesticides, and arsenic
- Chemotherapy and radiation therapy for cancer treatment
- Various infectious diseases, including hepatitis, HIV, and Epstein-Barr virus (a type of herpesvirus), lupus, rheumatoid arthritis, or other autoimmune disorders (those in which the immune system attacks healthy cells)
- Certain drugs, including some antibiotics, immunosuppressants, and some nonsteroidal anti-inflammatory drugs (NSAIDs)
- Cancer that has spread to the bone
Causes of inherited aplastic anemia, which is rare and develops from genes that are passed down from parent to child, include:
- Fanconi anemia
- Diamond–Blackfan anemia
- Shwachman–Diamond syndrome
- Dyskeratosis congenita
While blood tests can detect low blood cell counts and the possibility of aplastic anemia, they cannot diagnose the disorder.
Sickle cell anemia occurs when a person inherits two sickle hemoglobin genes, one from each parent.
A person who inherits a sickle hemoglobin gene from one parent and a normal hemoglobin gene from the other parent is said to have sickle trait.
People with sickle trait generally don't have symptoms related to it, but they are at risk of developing certain medical problems, and they can pass on the sickle hemoglobin gene to their children.
Sickle cell anemia affects millions of people around the world. It's most common in people who have ancestors from sub-Saharan Africa; regions in the Western Hemisphere (South America, the Caribbean, and Central America); Saudi Arabia; India; and Mediterranean countries such as Turkey, Greece, and Italy. (7)
In the United States, the condition affects 90,000 to 100,000 people, and mainly affects Black Americans or African Americans. (7)
The prevalence of the gene mutation that causes sickle cell is higher in areas of the world where malaria is found. Researchers have found that having sickle cell trait offers some survival advantage against malaria.
West and Central Africa are particularly hard hit, with a form of sickle cell anemia affecting about 1 to 2 percent of all births, according to the Sickle Cell Disease Association of America. (7)
In the United States about 70,000 to 100,000 people have sickle cell anemia, and African Americans are affected most often, with 1 out of 365 Black American babies born with sickle cell anemia, reports the National Heart, Lung, and Blood Institute (NHLBI). (8)
Pernicious anemia occurs when the body can't absorb enough vitamin B12 from food because it lacks a protein in the stomach called intrinsic factor, caused by autoantibodies to intrinsic factor or parietal cells. If you lack intrinsic factor, there is nothing you can do to prevent pernicious anemia caused by this.
Pernicious anemia can run in families, so having family members with the condition puts you at risk.
Since people with pernicious anemia cannot effectively absorb B12, they must receive supplemental B12 through injections or very high oral doses while monitoring blood tests. (23)
In rare cases, another form of B12-related anemia, megaloblastic anemia, occurs simply because you're not eating enough B12. In these cases, eating foods high in B12 can help the condition. Such foods include: (14)
- Beef, liver, poultry, and fish
- Eggs and dairy products
- Soy-based drinks and veggie burgers
- Breakfast cereals with added vitamin B12
B12 deficiency can also be caused by other factors and conditions, such as infections, surgery, medicines.
Anemia of chronic disease can be caused by the following chronic conditions: (13)
Inflammatory diseases, which are conditions that produce an inflammatory response in the body can cause anemia of chronic disease for several reasons:
- The inflammatory response can produce cytokines, a protein that protects the body against infection and interferes with iron processing and red blood cell production.
- Inflammation can cause internal bleeding that leads to a decrease in red blood cell count.
- Inflammation of the gastrointestinal system can interfere with the body's ability to absorb iron from food.
Types of inflammatory disease known to cause anemia of chronic disease include:
- Rheumatoid arthritis (RA)
- Ulcerative colitis
- Crohn's disease
- Inflammatory bowel disease
- Degenerative joint disease
Infectious diseases can cause anemia of chronic disease if a person's immune system's response to the infection interferes with red blood cell production.
As with inflammatory diseases, infectious diseases can cause the immune system to release cytokines, which can interfere with the body's ability to use iron to create red blood cells. Cytokines also can block the production and function of erythropoietin, a hormone produced by the kidneys that prompts a person's bone marrow to produce red blood cells.
Infectious diseases known to lead to anemia of chronic disease include:
Kidney failure in people with kidney disease can cause anemia of chronic disease if the disease interferes with the kidneys' production of erythropoietin. Diseased kidneys also can cause the body to absorb less iron and folate, nutrients necessary to the creation of red blood cells.
People with kidney failure also might experience iron deficiency as a result of blood loss that occurs during hemodialysis.
Certain types of cancer can prompt the release of inflammatory cytokines, which interfere with erythropoietin production and creation of red blood cells by the bone marrow. These cancers include:
Cancer also can harm red blood cell production if it invades the bone marrow. Moreover, cancer treatments like chemotherapy and radiation therapy can lead to anemia of chronic disease if they damage the bone marrow.
How Is Anemia Diagnosed?
In order to determine if you have anemia, your doctor will most likely talk to you about your medical and family history, give you a physical exam, and perform the following tests: (1)
- Complete blood count (CBC) A CBC will reveal the number of blood cells in a blood sample. To determine if you have anemia, your doctor will look at your blood's number of red blood cells (hematocrit) and hemoglobin.
Doctors may have different target numbers, but normal adult hematocrit values tend to range from 40 percent to 52 percent for men and 35 percent to 47 percent for women. Target adult hemoglobin values are generally 14 to 18 grams per deciliter for men and 12 to 16 grams per deciliter for women. (1)
- A test that looks at size and shape of red blood cells, called a peripheral smear Your doctor may run a test to determine if your red blood cells have an unusual size, shape, and color. (1)
- Additional tests Your doctor may recommend an invasive test to gather a sample of your bone marrow if you are diagnosed with anemia. This can help determine the cause. (1)
Prognosis of Anemia
The prognosis of anemia depends on its type.
Most people with iron-deficiency anemia will recover fully. But if the condition is not corrected, and chronic iron deficiency persists until the red cell count and hemoglobin levels get extremely low, it can be fatal. (15)
While prognosis varies from person to person, the condition can be short-lived for those who develop aplastic anemia because of medications, pregnancy, low-dose radiation or infectious mononucleosis. The condition can be life-threatening if it's severe and lasts a long time or if treatments are not effective. (16)
For those who do not recover, they may receive a bone marrow transplant from a sibling or other matched donor; their prognosis is better than for those who receive a transplant from a donor unrelated to them. And the prognosis is increasingly reported to be favorable.
For older patients with acquired aplastic anemia, when immunosuppressive therapy is the only option, about 50 percent of people will respond well to it. (16)
People with aplastic anemia are at higher than average risk of developing leukemia. (25)
Sickle cell anemia
While there is no cure for sickle cell anemia, treatments can help with pain management and with preventing complications.
Improved treatments have given a better outlet for people with sickle cell anemia. As little as 40 years ago, almost 15 percent of children born with sickle cell anemia died before age 2, and many more died as teens, according to the NHLBI. (24)
Pernicious anemia, once it manifests, will require treatment for the duration of one's life, yet treatment is well tolerated and the disorder should not cause significant hardship.
In some studies, they have shown having pernicious anemia increases the chances of developing stomach cancer. (26)
Anemia of chronic disease
If the underlying condition that is causing anemia of chronic disease gets treated, the condition can resolve as a result. (12)
Duration of Anemia
The duration of anemia depends on the type.
Iron deficiency anemia
Iron supplements (prescribed by your physician or hematologist) taken orally can work within 3 to 10 days to increase the body's production of red blood cells; however, it typically takes months to bring iron levels back to normal. (17)
When aplastic anemia is caused by radiation, chemotherapy, and other drugs, the condition tends to subside once treatments stop. (19)
For women who develop aplastic anemia when pregnant, the condition usually improves once they're no longer pregnant. (19)
Sickle cell anemia
Having sickle cell anemia means having a lifelong condition because a blood and bone marrow transplant are the only cure, and a small percentage of people with the disease actually get the transplant. (8)
While pernicious anemia is a lifelong condition, treatment can help people feel well and live normal lives. In most cases, early diagnosis and treatment can help reverse complications of pernicious anemia, such as nerve damage. (14)
Anemia of chronic disease
When the underlying condition that is causing anemia of chronic disease is treated, the condition tends to go away.
Treatments and Medication Options for Anemia
Each type of anemia will require a different type of treatment. (1)
- Growth factors, both naturally occurring and man-made, are hormones that stimulate bone marrow to make blood cells to treat aplastic anemia. Immunosuppressive drug therapy is another option.
- Severe iron-deficiency anemia may require intravenous (IV) iron therapy, blood transfusion, or injections of the synthetic hormone erythropoietin, which is normally produced by the kidneys.
- When successful, a bone marrow transplant or stem cell transplant may cure sickle cell anemia.
- B12 supplements or shots may help pernicious anemia.
- Chemotherapy or bone marrow transplantation may be needed for anemias associated with bone marrow disease.
- Oxygen, pain relievers, and oral and intravenous fluids can help reduce pain and prevent complications in sickle cell anemia.
Alternative and Complementary Therapies
- When low iron is caused by an inadequate diet lacking iron-rich foods, a focus on high-iron foods such as meat, poultry, fish, beans, tofu, dried fruits, dark green leafy vegetables, and iron-fortified foods like breads and cereals can help.
- Eating or drinking foods and drinks high in vitamin C, such as orange juice, broccoli, peppers, and more, can help your body absorb iron when you eat it. (1)
Prevention of Anemia
In some instances, iron-deficiency anemia can be prevented with the following methods: (18)
- Treating blood loss For those with heavy menstrual periods or stomach issues, such as frequent diarrhea or blood in your stool, addressing the root imbalances leading to blood loss can help prevent anemia.
- Consuming foods with iron Eating foods with high levels of iron, such as lean meat, chicken, dark leafy vegetables, and beans can increase iron levels.
- Ensuring enough vitamin C Drinks and foods with vitamin C like orange juice, strawberries, and broccoli can help the body absorb iron.
- A balanced diet Balanced diets can ensure enough iron is being consumed.
- Limiting coffee or tea with meals If you drink coffee and tea with meals, they can make it difficult for your body to absorb iron.
- Caution with calcium pills Because calcium can affect how your body absorbs iron, ask your doctor what the best approach is for getting both enough calcium and enough iron.
While there's no known prevention for aplastic anemia, staying clear of insecticides, herbicides, organic solvents, paint removers, and other toxic chemicals may lower your risk. (19)
While pernicious anemia caused by a lack of intrinsic factor is not preventable, those who develop the disease because they lack B12 in their diet can potentially reduce the impact by eating foods high in B12, such as beef, eggs, fortified cereal, and more, yet ultimately they are likely to need high-dose B12 supplementation or injections under their doctors' guidance. (14)
Complications of Anemia
When anemia is not treated, it can cause complications, including: (1)
- Extreme fatigue resulting in the inability to function.
- Pregnancy complications, including premature birth.
- Heart problems, such as irregular heartbeat, enlarged heart, and heart failure.
- Death caused by loss of blood with sickle cell anemia.
Research and Statistics: Who Has Anemia?
Anemia affects 1.62 billion people worldwide, and disproportionately occurs in countries with limited resources, according to the WHO. Children who are preschool age are greatly affected. Nonpregnant women have the greatest prevalence, while men experience the lowest occurrences. As the most common blood condition in the United States, anemia affects three million Americans. (20)
Related Conditions and Causes of Anemia
In some cases, B12 deficiency can be caused by conditions such as infections, surgery, medicines, and diet.
Crohn's and celiac disease can also interfere with B12 absorption.
Anemia of chronic disease can be caused by inflammatory diseases, such as rheumatoid arthritis, ulcerative colitis, Crohn's disease, inflammatory bowel disease, lupus, diabetes, and degenerative joint disease. (13)
Infectious diseases, such as HIV, hepatitis, tuberculosis, heart infection, and bone infection, can also lead to anemia of chronic disease.
Additionally, kidney failure and cancers, such as Hodgkin disease, non-Hodgkin lymphoma, and lung and breast cancer, can cause anemia.
Iron-Deficiency Anemia Quiz
Sometimes getting the right amount of iron from your diet isn't enough if your body isn't able to absorb it properly. For instance, people who've had intestinal surgery, such as gastric bypass, or those with Crohn's disease or celiac disease, may have trouble absorbing iron. Iron absorption can also be limited by prescription medicines that reduce acid in the stomach. (10)
Blood loss is another cause of iron deficiency anemia because whenever you lose blood from your body, iron loss also occurs. If you don't have enough iron stored in your body to make up for the iron lost in your blood, you can develop anemia.
- Heavy menstrual periods
- Bleeding fibroids (noncancerous growths) in the uterus
- Internal bleeding caused by an ulcer, colon polyp, colon cancer, urinary tract bleeding, or use of pain medications
- Injuries or surgery
- Repeated blood drawings
Symptoms of iron-deficiency anemia vary depending on how severe your anemia is. If you have mild to moderate iron-deficiency anemia, you may not have any signs or symptoms. But as the condition worsens, you may experience: (11)
- Pale skin
- Shortness of breath
- Chest pain
- Frequent infections
- Dizziness or light-headedness
- Cold hands and feet
- Swelling or soreness of your tongue
- Cracks around your mouth
- Brittle nails
- Fast heartbeat
- Poor appetite
- Restless legs syndrome
- Enlarged spleen
- Cravings for nonfood items, such as ice, dirt, paint, or starch
If you're mildly anemic, your doctor may recommend a diet filled with iron-rich foods. The foods with the highest iron content are:
- Meat, especially beef and liver
- Poultry — chicken livers are packed with iron
- Fish and shellfish, especially oysters
- Leafy greens, like kale, spinach, and broccoli
- Beans and peas
- Iron-enriched breads, pastas, and cereals
Take note that iron from vegetable sources is less readily absorbed than iron from meat, poultry, or seafood.
With all forms of anemia, tiredness or fatigue is the most common symptom because of low red blood cell count. Shortness of breath, dizziness, headache, coldness in your hands and feet, pale or yellowish skin, and chest pain are other signs.
When you have low red blood cells, your heart has to work harder to move oxygen-rich blood through your body. When this occurs, you can experience irregular heartbeat, enlarged heart, or even heart failure.
If your doctor suspects you may have pernicious anemia, he or she can confirm it with blood tests. Bone marrow tests can also detect this type of anemia because when pernicious anemia is present, bone marrow cells that turn into blood cells are larger than normal. (14)
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