To evaluate hyperlipidemia as an index to coronary artery disease Investigation of serum lipids is indicated in those with coronary and other arterial disease, especially when it is premature, and in those with family history of atherosclerosis or of hyperlipidemia. In this sense, the expression "premature" is mostly used to include those younger than 40 years of age. In addition to application in screening programs for evaluation of risk factors for coronary arterial disease, lipid profiling may lead to detection of some cases of hypothyroidism. PRIMARY HYPERLIPOPROTEINEMIA includes hypercholesterolemia, a direct risk factor for coronary heart disease. SECONDARY HYPERLIPOPROTEINEMIA includes increases of lipoproteins secondary to hypothyroidism, nephrosis, renal failure, obesity, diabetes mellitus, alcoholism, primary biliary cirrhosis, and other types of cholestasis. DECREASED lipids are found with some cases of malabsorption, malnutrition, and advanced liver disease.