VERY HIGH HDL CHOLESTEROL LEVELS - BOON OR BANE

CBC and Lipid profile. CBC was WNL while chol (211 mg/dl), Triglyceride (109 mg/dl) and HDL was

unusually high (113 mg/dl). On further investigations and detailed history it was found that he was a farmer, was nonalcoholic, non-diabetic, normotensive, nonsmoker and had not received any medications for reducing his lipids . He had never undergone any blood tests previously. He complained of headache off and on for which a CT scan was performed and which revealed focal area of hypoattenuation in right anterior centrum semiovale, corona radiate and right lentiform nucleus suggestive of recent right MCA territory infarct. High density lipoprotein or HDL is often called the good cholesterol. It has long been accepted that the HDL is more tightly controlled by genetic factors than are the other lipoproteins (ie, LDL, VLDL, intermediate-density lipoprotein [IDL], and chylomicrons). For example, in certain families, especially some families with Japanese ancestry, a genetic deficiency of cholesteryl ester transfer protein (CETP) is associated with strikingly elevated HDL cholesterol levels. However, environmental factors also have a significant impact on HDL levels. Factors that elevate HDL concentrations include chronic alcoholism, treatment with oral estrogen replacement therapy, extensive aerobic exercise, and treatment with niacin, statins, or fibrates. On the other hand, smoking reduces levels of HDL cholesterol, while quitting smoking leads to a rise in the plasma HDL level. Very high levels of HDL cholesterol have been reported to be atherogenic. The mechanism of this paradoxical effect is not entirely clear. Conclusion: While the epidemiology indicates a strong inverse association between HDL-C and CVD risk, at both extremes of HDL-C distribution, genetic conditions that influence HDL metabolism have a far less predictable relationship to atherosclerosis. Ongoing studies of genetic causes of very high HDL-C also promise to provide similarly important insights on the complex relationship between HDL metabolism and atherosclerosis that could lead to new therapies for the treatment of atherosclerotic CVD.

Key words: HDL, good cholesterol, CETP (Cholesteryl Ester Transfer Protein), HL (Hepatic Lipase), EL

(Endothelial Lipase). Scavenger receptor class B type I(SRB 1). RCT (Reverse cholesterol Transport) HALP (hyeralphalipoproteinemia)