Hypercholesterolemia is a condition in which greater than normal amounts of cholesterol are present in the blood. High levels of cholesterol and other lipids may lead to the development of atherosclerosis. Hypercholesterolemia may be reduced or prevented by avoiding saturated fats, which are found in red meats, eggs, and dairy products, or certain medications. Hypercholesterolemia is sometimes inherited; in such cases diet is a less effective factor. Lipids are insoluble in water but soluble in alcohol, schoroform, ether, and other solvents. They are stored in the body and serve as an energy reserve, but are elevated in various diseases such as atherosclerosis. The kinds of lipids are cholesterol, fatty acids, neutral fat, phospholipids, and triglycerides. The normal concentrations of total lipids in serum are 400 to 800 mg/dl; cholesterol, 150 to 250 mg/dl; fatty acids, 9 to 15 mM/L; neutral fat, 0 to 200 mg/dl; phospholipids, 150 to 380 mg/dl; triglycerides, 10 to 190 mg/dl. There is good cholesterol and bad cholesterol. The good cholesterol is called high-density lipoprotein (HDL). The bad cholesterol is called low-density lipoprotein (LDL). .
In the bloodstream, cholesterol and triglycerides (TG) as part of lipoprotein complexes. With ultracentrifugation, these complexes separate into very-low-density lipoprotein (VLDL) intermediate-density lipoprotein (IDL), and low-density lipoprotein (LDL) fractions that contain apolipoprotein B-100 and high-density lipoprotein (HDL) fractions. Cholesterol and triglycerides synthesized in the liver are incorporated into VLDL and secreted into the circulation for delivery to peripheral tissues. TG are removed by the action of lipases, and in a series of steps, the modified VLDL is transformed first into IDL and then into cholesterol-rich LDL. IDL and LDL are removed from the circulation mainly by high affinity ApoB/E receptors, which are expressed to the greatest extent on liver cells.
