Hypercholesterolemia Description

Hypercholesterolemia Description

Cholesterol is a waxy or fatty substance that the human body produces normally. About 75 percent of the cholesterol in the body is made by the liver and other cells; the remaining 25 percent comes from food. A certain amount of cholesterol is necessary to maintain the function of cell membranes; thus cholesterol is present in the walls of all body cells, including those in the skin, muscle tissue, nervous system, digestive tract, and other parts of the body.

The body also needs cholesterol to make bile (a substance produced in the liver that helps to digest fat), hormones, and vitamin D. This cholesterol is carried in the bloodstream attached to protein molecules. These combinations of cholesterol and protein molecules are called lipoproteins. If more cholesterol is made than is needed for the body’s functions, the waxy cholesterol may form deposits on the inner walls of arteries known as plaques.

Fatty plaque deposits are particularly likely to build up in the arteries that supply the heart with blood. These blood vessels are known as the

coronary arteries. Plaque deposits can become thick enough to partially block the coronary arteries. If the deposits remain in place, they eventually cause the arteries to stiffen or harden—a condition known as atherosclerosis. If the arteries become too narrow because of the plaques, they cannot carry enough blood to the heart to meet the needs of the heart muscle for oxygen. The oxygen-starved muscle may then produce a kind of chest pain known as angina. The fatty plaques can also come loose from the walls of the artery, resulting in the formation of a clot, a complete blockage of the coronary artery, and a heart attack.

It is important to understand that there are three different types of cholesterol and lipoproteins in the human body:

• Low-density lipoprotein (LDL). Often called “bad” cholesterol, LDL is the type of cholesterol that forms plaques on the walls of the coronary arteries.

• High-density lipoprotein (HDL). The “good” cholesterol, HDL picks up LDL and takes it back to the liver. Between 25 and 32 percent of the body’s cholesterol is HDL.

• Very low-density lipoprotein (VLDL). This type of cholesterol contains the highest levels of triglycerides (a type of fat) attached to its protein molecules. VLDL is converted in the bloodstream to LDL and can increase the size of LDL particles, thus speeding up the formation of plaques and atherosclerosis.