High density Lipoprotein; What to Measure: Quality or Quantity? Dear Editor,

Atherosclerotic coronary artery disease (CAD) affects both men and women and accounts for ap-proximately>4.5 million deaths annually in the developing countries.1 Atherogenic lipoproteins namely, low density lipoprotein (LDL) and lipoprotein remanants promote atherosclerosis, and high density lipoprotein (HDL) prevents it. However, in some instances increased plasma HDL concentrations can result from reduced catabolism due to blockade in the dynamic flow of HDL lipids from peripheral tis-sues to the liver. In such a scenario, measuring HDL concentration alone may not be accurate in as-sessing the cardio vascular risk. With literature review, Framingham study (HDL concentrations pre-dicting cardiovascular risk) reveals that 40 % of coronary events occurred in subjects with normal HDL levels.2 This has fueled our search in which measuring HDL Quality, rather than Quantity, would help in a better prediction of atherosclerotic coronary artery disease. High density lipoprotein is believed to have two important functions affecting the occurrence of atherosclerosis. One function is called reverse cholesterol transport, which may be conceptual-ized in terms of cholesterol efflux from the arterial macrophages. The lipid deposited at the site of atherosclerotic lesions are removed and transported to the liver or other cholesterol metabolizing tissues for catabolism. This involves specific transporters like ABC transporter A1 (ABCA1) an