Alternate Names: Acquired hyperlipoproteinemia; High blood cholesterol; High blood triglycerides; High cholesterol; High triglycerides; Hyperlipidemia

Causes and Risks:

Hyperlipidemia is caused by excess lipids or fatty substances in the blood and is an important risk factor in developing atherosclerosis and heart disease. Hyperlipidemia may be caused by genetic factors, as in certain familial diseases, or by secondary factors in acquired hyperlipidemia.

Forms of lipids in the blood are cholesterol, triglycerides, and lipoproteins, which are molecules of fat and cholesterol linked to protein. Types of lipoproteins are very low-density lipoproteins (VLDL), low-density lipoproteins (LDL) and intermediate-density lipoproteins (IDL). Chylomicrons are also classified as lipoproteins and are composed of triglycerides, cholesterol and protein. There are also high-density lipoproteins (HDL) that are inversely related to heart disease risk and are therefore known as "antirisk", or protective, factors.

There are 6 types of hyperlipidemia which are differentiated by the type(s) of lipids that are elevated in the blood. Some of the types may be due to a primary disorder such as a familial hyperlipidemia, and some are due to secondary causes. Secondary causes of hyperlipidemia are related to disease risk factors, dietary risk factors, and drugs associated with hyperlipidemia.

Disease risk factors include the following: insulin dependent diabetes mellitus; non-insulin dependent diabetes mellitus; hypothyroidism; Cushing’s syndrome; and certain types of renal failure. Drug risk factors include: birth control pills; hormones such as estrogen and corticosteroids; certain diuretics; and beta-blockers. Dietary risk factors include: dietary fat intake greater than 40% of total calories; saturated fat intake greater than 10% of total calories; cholesterol intake greater than 300 milligrams per day; habitual excessive alcohol use; and obesity. Cigarette smoking is a lifestyle risk factor for hyperlipidemia.

The incidence is 1 out of 100 people and is higher among men than women.

Prevention:

Screening for hyperlipidemia should be a part of a routine health evaluation. Recommendations vary, but usually patients should be screened every five years, usually starting sometime between the ages of 20 and 30. Reducing dietary risk factors by maintaining ideal body weight, eating a well balanced, low fat diet, and limiting cholesterol intake will help prevent the onset of hyperlipidemia.

References:

Scandinavian Simvastatin Survival Study Group. Randomised trial of cholesterol lowering in 4,444 patients with coronary heart disease: The Scandinavian Survival Study (4S). Lancet 1994; 344:1383.

Grundy SM, Balady GJ, Criqui MH, et al. When to start cholesterol-lowering therapy in patients with coronary heart disease. A statement for healthcare professionals from the American Heart Association Task Force on Risk Reduction. Circulation 1997; 95:1683.

Symptoms:

There are no symptoms.

Signs and Tests:

Physical examination (may display xanthalasmata on the skin) and laboratory tests may be performed to identify secondary causes of hyperlipidemia or familial disorders if lipoprotein analysis is elevated. Results of a lipoprotein analysis that indicate hyperlipidemia include:

• total cholesterol level greater than 200
• LDL cholesterol level greater than 130
• fasting coronary risk profile triglycerides greater than 250

Note: Normal values for cholesterol and triglycerides are dependent on age.

This disease may also alter the results of the following tests:

• apolipoprotein CII
• apolipoprotein B100

Treatment:

The goal of therapy is to reduce the risk of atherosclerosis and cardiovascular disease through therapy aimed at lowering the blood lipid levels.

Dietary modification is the initial step in treatment for most patients with mild to moderate hyperlipidemia. For overweight individuals, weight reduction to ideal body weight is recommended. Reduction of total calories, cholesterol, and saturated fat is appropriate for most people. The degree of dietary restriction is proportional to the degree of the hyperlipidemia.

If there is no improvement in lipid blood levels within 2 months after maximal dietary modification, or if the initial cholesterol level is severely elevated, drug therapy is generally initiated. The type of drug chosen depends upon the type of lipoprotein elevated in the serum. Several types of medications are available. Bile sequestrant resins, cholestyramine, colestipol, and nicotinic acid are drugs that may be prescribed for mild to moderate hyperlipidemia.

The class of drugs prescribed for the most common cause of hyperlipidemia is the HMG-coA reductase inhibitors. These drugs, also known as the statins, are prescribed for patients with elevated LDL levels. Most patients with a history of heart attack or high risk for heart attack who have high cholesterol should be prescribed one of these medications. The statins have been shown in studies to reduce death from heart attacks in patients with a history of coronary artery disease. (DON’T STOP TAKING PRESCRIPTION MEDICATION WITHOUT CONSULTING YOUR HEALTH CARE PROVIDER.)

Prognosis:

Drug and diet therapy is likely to continue throughout the life of the affected individual. Periodic monitoring of blood levels is necessary to determine the response to treatment. In studies, reduction of high cholesterol levels has shown a decrease in the progression of atherosclerosis.

Complications:

• atherosclerosis
• coronary artery disease

This condition is usually found by the health care provider when a screening test is performed. If you have hyperlipidemia, be aware that you are at increased risk for heart disease.

Call for an appointment with your health care provider if you have this condition and have not scheduled periodic monitoring of blood lipid levels.