Hyperlipidemia is a family of disorders that are characterized by abnormally high levels of lipids (fats) in the blood. While fats play a vital role in the body’s metabolic processes, high blood levels of fats increase the risk of coronary heart disease (CHD).
Two common lipid abnormalities are characterized either by high blood cholesterol levels (hypercholesterolemia) or high blood levels of triglycerides (hypertriglyceridemia). Cholesterol is manufactured primarily in the liver and then carried in the bloodstream by low density lipoprotein (LDL). (Because cholesterol and other fats do not dissolve in water, they cannot travel through the blood unaided. Lipoproteins are particles formed in the liver to transport cholesterol and other fats through the bloodstream.) Cholesterol is returned to the liver from other body cells by another lipoprotein, high density lipoprotein (HDL). From there, cholesterol is secreted into the bile, either unchanged or after conversion to bile acids.
Cholesterol is essential for the formation of cell membranes and the manufacture of several hormones, but it is not required from the diet because the liver produces all the cholesterol the body needs. If blood cholesterol levels are elevated, large amounts of LDL (so-called “bad”) cholesterol can deposit in the arterial walls. These deposits represent the first stage in the narrowing of arteries, termed atherosclerosis. Because hypercholesterolemia causes no symptoms, preventive measures and regular measurement of cholesterol levels are important for people in high-risk categories. Hypercholesterolemia is especially dangerous when HDL (“good”) cholesterol levels are low. Left untreated, hypercholesterolemia can eventually lead to a heart attack due to CHD or a stroke due to narrowed arteries supplying the brain.
Hypertriglyceridemia is characterized by high blood levels of triglycerides, which are the body’s main source of stored energy. Like cholesterol, triglycerides are obtained from food and manufactured in the liver. Also like cholesterol, triglycerides require lipoproteins for their transport in the blood. Most of the triglycerides in blood are carried by very low density lipoprotein (VLDL); dietary triglycerides are carried from the intestine on other lipoproteins called chylomicrons. Elevations in blood triglycerides may promote atherosclerosis by altering the size, density, and composition of LDL. In addition, very high blood triglyceride levels can lead to inflammation of the pancreas (pancreatitis).
Treatment of hyperlipidemia involves reducing lipid levels through lifestyle measures and, if necessary, medications to lower the risk of CHD and stroke.
What Causes Hyperlipidemia?
- Hereditary factors are the most common cause.
- A diet high in saturated fat and cholesterol increases blood cholesterol and triglyceride levels.
- Other disorders, such as diabetes mellitus, kidney disease, and hypothyroidism, may promote hypertriglyceridemia.
- Certain drugs, such as estrogen, corticosteroids, retinoids, protease inhibitors, thiazide diuretics, and beta-blockers, may cause hypertriglyceridemia.
- Obesity increases the risk of hyperlipidemia.
- Chronic, excessive alcohol use increases the risk of hypertriglyceridemia.
- Smoking and not exercising may lead to hyperlipidemia.
- Steroid uses, alcoholism, hypothyroidism, oral contraceptives, chronic renal failure, hypopituitarism and nephritic syndrome are other contributors to hyperlipidemia.
Symptoms of Hyperlipidemia
- If hyperlipidemia results in CHD or atherosclerosis at other sites, symptoms may include chest pain (angina), heart attack, or stroke.
- Hyperlipidemia itself does not produce symptoms. When levels are exceedingly high, cholesterol may be deposited (xanthomas) in tendons or just beneath the skin under the eyes. Very high triglyceride levels may result in the formation of nodules on the elbows or knees, or the appearance of multiple, pimple-sized, yellowish skin eruptions.
- The skin deposits fats or xanthomas
- Swelling of organs such as the liver, spleen, or pancreas (pancreatitis)
- Blockage of blood vessels in brain and heart
Prevention of Hyperlipidemia
- Eat a diet low in saturated fats and cholesterol to prevent lipid abnormalities.
- Eat foods high in soluble fiber such as oats, beans, peas and certain fruits.
- Exercise regularly.
- Maintain a healthy weight—or lose weight, if necessary.
- Moderate alcohol consumption increases levels of HDL cholesterol, which decreases the risk of CHD. However, chronic, heavy alcohol use raises triglyceride levels, and is associated with many other harmful effects. Therefore, it is recommended that, on average, women consume no more than one alcoholic beverage per day; men should consume no more than two alcoholic drinks daily. (A drink is considered one 12-ounce beer, 4 ounces of wine, or 1.5 ounces of 80-proof spirits.)
- The National Cholesterol Education Program (NCEP) recommends that all adults 20 years and older obtain a fasting lipid profile—a blood test that measures total cholesterol, LDL cholesterol, HDL cholesterol, and triglycerides—at least every 5 years. Those with known risk factors, such as diabetes or a family history of CHD, may need to be screened more frequently.
How to Treat Hyperlipidemia
- Underlying causes of the disorder, such as diabetes and hypothyroidism, should be treated.
- Lifestyle changes, including eating a diet low in saturated fats and cholesterol, can have a great impact on lipids. Other dietary measures include the use of foods that contain plant stanols and sterols, which are added to certain margarines and salad dressings, and consuming foods rich in soluble fiber, such as cereal grains, legumes, and many fruits and vegetables.
- Weight loss is the most effective way to lower triglyceride levels.
- Quitting smoking and exercising may raise levels of “good” HDL cholesterol.
- Medications specifically designed to reduce blood cholesterol levels, such as bile acid sequestrants (cholestyramine, colestipol, and coesevelam), statins (lovastatin, pravastatin, simvastatin, fluvastatin, and atorvastatin), or niacin, may be prescribed when dietary modifications prove inadequate.
- Statins, niacin, or fibrates (gemfibrozil, fenofibrate) can be used to lower triglyceride levels when lifestyle measures fail to produce adequate results. Hypertriglyceridemia often requires treatment with a combination of a fibrate and a statin.
- In rare patients with extremely high cholesterol levels (familial hypercholesterolemia), repeated removal of blood plasma (plasmapheresis) may be recommended to lower blood cholesterol levels.
- Most people require long-term, even lifelong, treatment of hyperlipidemia with both lifestyle measures and medications.
When to Call a Doctor
- Make an appointment with your doctor to check your lipid profile at least every five years. If you are at high risk for CHD or if any member of your immediate family has hypercholesterolemia, hypertriglyceridemia, or premature CHD or stroke, you need to be screened more regularly.
Johns Hopkins Symptoms and Remedies: The Complete Home Medical Reference
Simeon Margolis, M.D., Ph.D., Medical Editor
Prepared by the Editors of The Johns Hopkins Medical Letter: Health After 50
Updated by Remedy Health Media