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.