HDLs have the opposite function to that of LDLs in which they deleted cholesterol from the tissues. The HDLs are synthesized in the blood mainly from components derived from the degradation of other lipoproteins. HDLs then get their cholesterol through extracting it from cell membranes and converting it into cholesterol esters by the action of LCAT .The HDLs are then either taken up straightly by the liver or transfer their cholesterol esters to VLDLs, of that about half are taken up by the liver via receptor-mediated endocytosis . The liver is the only organ which can dispose of significant quantities of cholesterol and primarily in the form of bile salts.