[Causes and Abnormal Lipid Laboratory Values of Secondary Hyperlipidemia: Endocrine Disease]

Secondary hyperlipidemia is common and occurs frequently in patients with endocrine disease such as hy- pothyroidism, Cushing's syndrome, and acromegaly, metabolic disease such as diabetes mellitus, renal dis- ease such as nephrotic syndrome and chronic renal failure, liver disease such as obstructive liver disease, and as a side-effect of glucocorticoids and estrogens. The underlying cause of high serum lipid levels will often be missed if it is not actively sought. We describe. the causes and abnormal lipid laboratory values of sec- ondary hyperlipidemia in endocrine disease patients such as those with hypothyroidism, Cushing's syndrome, and acromegaly. Hypothyroidism is associated with elevated serum total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C), and normal or elevated high-density lipoprotein cholesterol (HDL-C) and triglycerides (TG), respectively. The lipid abnormalities are due to the reductions in hepatic LDL receptor function and hepatic TG lipase (HTGL) activity. Cushing's syndrome is associated with elevated serum TC, LDL-C, and TG and elevated or normal HDL-C. The lipid abnormalities are due to the glucocorticoid- induced increase in very low-density lipoprotein (VLDL) and elevation in lipoprotein lipase (LPL) activity. Acromegaly is associated with normal serum TC, reduced LDL-C and HDL-C, and elevated TG. The lipid abnormalities are due to the growth hormone-induced reductions in LPL and HTGL activity and increase in hepatic LDL receptors. When we examine hyperlipidemic patients, it is important to diagnose the true name of the disease, usually in consideration of the possibility of the cause of secondary hyperlipidemia. [Review].