Lipid Disorders

Definition

Acquired lipid disorders is a group of disorders characterized by an excess of fatty substances, such as cholesterol, triglycerides, and lipoproteins present in the blood.

Alternative Names

Acquired hyperlipoproteinemia; High blood cholesterol; High blood triglycerides; High cholesterol; High triglycerides; Hyperlipidemia

Causes, incidence, and risk factors

Lipid disorders are caused by excess lipids or fatty substances in the blood, and are an important risk factor in developing atherosclerosis and heart disease. Certain types of lipid disorders may be caused by genetic factors, as in certain familial diseases, or by secondary factors, such as fatty diets and diabetes.

Forms of lipids in the blood are cholesterol, triglycerides, and lipoproteins, which are molecules of fat and cholesterol linked to protein. Types of lipoproteins include 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. High-density lipoproteins (HDL) "good cholesterol" 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 types may be caused by 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: Type I diabetes mellitus, Type II 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 with hyperlipidemia increases the risk for heart disease.

Hyperlipidemia is more common in men than women.

Symptoms

There are no symptoms.

Signs and tests

Physical examination (may display xanthalasmata, or fat deposits, on the skin) and laboratory tests may be performed to identify secondary causes of hyperlipidemia or familial disorders, if lipoprotein analysis is elevated.

Fasting lipid (or lipoprotein test) analysis breaks down cholesterol into four groups:

A defined "high" cholesterol (lipid) level depends on other risk factors including smoking, high blood pressure, low HDL, family history of heart disease, male over 45 or woman over 55. Total cholesterol values over 200 may indicate an increased risk for heart disease.

However, LDL levels better predict risk factor for heart disease. Those with known heart disease (previous heart attack or peripheral vascular disease) or diabetes should have levels under 100.

LDL over 130, with two or more of the above risk factors, is abnormal. An LDL over 160, with one or fewer of the risk factors, is also abnormal. HDL cholesterol more than or equal to 60 takes away one risk factor and decreases your risk for heart disease. Levels under 40 add a risk factor.

Normal triglyceride levels are under 150. However, as with other components of the lipid test, fasting less than 9-12 hours may alter triglyceride results.

Other tests to help determine risk for heart disease are:

Discuss your results with your health care provider to determine the best therapy for your lifestyle.

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.

Expectations (prognosis)

Drug and diet therapy usually need 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

Calling your health care provider

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.

Prevention

Screening for hyperlipidemia should be a part of a routine health evaluation. Recommendations vary, but usually patients should be screened every two years, 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.

Unless otherwise noted: this document was originated by, reviewed and/or edited by Tripp Bradd, MD
current revision/review: 8/26/2008