What Do Cholesterol Numbers Mean?

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By Erik Steel
eHow Contributing Writer

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Cholesterol is a waxy steroid found both naturally in our systems and also in the food we eat. It is a necessary chemical in the synthesis of body chemicals like hormones, but too much cholesterol in blood increases risk for heart disease, stroke and other serious health problems. It is important to understand cholesterol and its two forms, HDL ("good" cholesterol) and LDL ("bad" cholesterol) as well as how cholesterol works so that you can maintain or return to healthy levels.

Features

Cholesterol is part of the subset of organic compounds (those that contain carbon) called lipids; according to lipidmaps.org, cholesterol is found in both cell membranes and blood plasma. Its name derives from the Greek words for bile and solid, which is appropriate due to the body's method of recycling and disposing of cholesterol; the liver changes cholesterol into bile acid, which is then reabsorbed or excreted, according to a paper by AW Wolkoff and DE Cohen. Because of the participation of cholesterol in this process, it is a major component of gallstones, in which it was first found.

Significance

Because cholesterol is found in cell membranes, where it regulates the passage of chemicals across the membrane and is also involved in endocytosis (bringing materials into cells), it is a common molecule in the human body. It is also found, according to research by J.J. Bubis and M. Wolman, in myelin sheaths, which conduct nerve signals. The bile production of the liver, which makes use of cholesterol, is important in the absorption of fat-soluble vitamins.

Types

Cholesterol is transported through the body in the form of lipoproteins, which are molecules that contain both lipids and proteins. Two types of cholesterol are important in medical terms: LDL (low-density lipoprotein) and HDL (high-density lipoprotein). LDL cholesterol is associated with atherosclerosis, a plaque-forming condition linked to heart disease and stroke, although because it is used by the body for other functions, it is desirable in some quantity. HDL cholesterol, meanwhile, helps move LDL back through its recycling and excretion cycle by capturing and returning it to the liver.

Levels

The American Heart Association (AHA) defines three groups of total serum level (the combination number of both types of cholesterol): below 200 milligrams per deciliter is considered optimal, between 200 and 239 mg/dL is borderline for risk, and 240 or above is considered high risk. The AHA reports that a total blood serum cholesterol count above 200 requires further testing to determine the ratio of LDL to HDL cholesterol, since it is possible that there may simply be increased levels of HDL ("good" cholesterol). Below 100 mg/dL of LDL is considered optimal, but the "high" rating begins at 160 mg/dL; in healthy individuals, around 30 percent of cholesterol is high-density. It is also possible to have levels of HDL cholesterol that are too low (below 40mg/dL); you can work with your doctor to improve this number.

Prevention/Solution

The AHA lists a number of tips to reach and maintain healthy cholesterol levels, including avoiding or quitting smoking, getting exercise, and eating well (i.e., adding fiber, avoiding trans fats, avoiding high-cholesterol foods like eggs, cheese and meat). There are also a number of drug therapies available to help you reach healthy cholesterol levels; see Resources below for more information.