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Also called: Serum Cholesterol, Blood Cholesterol

- Summary
- About cholesterol
- About high cholesterol
- Understanding the numbers
- LDL and higher risk patients
- Frequency of screening
- Gender differences
- Questions for your doctor

Reviewed By:
Abdou Elhendy, MD, PhD, FACC, FAHA
Sumit Verma, M.D., FACC
Kerry Prewitt, M.D., FACC


Cholesterol is a waxy fat that is present in all human beings. About 80 percent of the cholesterol in the body is manufactured by the liver. The rest is consumed through cholesterol-rich foods such as meat, eggs and dairy products.

Cholesterol itself is vital for survival. However, it can also contribute to coronary artery disease. To understand how cholesterol is related to heart disease, it is necessary to understand how it is transported through the body. Cholesterol is carried in the bloodstream in specialized protein packages called lipoproteins. These are comprised of another building block called apolipoproteins.

A good analogy is to think of lipoproteins like vehicles on the road, while cholesterol represents the passengers. Some of the cars are sleek and fast, while others are cumbersome, large and slow. The nature of the lipoHigh cholesterol (hyperlipidemia) involves elevated blood cholesterol and/or triglyceride levels.protein package, or vehicles, ultimately determines what will happen to the cholesterol it carries. In some cases, excess cholesterol will be transported to the liver, where it is metabolized harmlessly. In other cases, excess cholesterol will penetrate the walls of arteries throughout the body, contributing to a disease called atherosclerosis.

Although there are many subclasses of lipoproteins, researchers generally focus on the following five types:

  • High-density lipoproteins (HDL), which transport cholesterol away from arteries and are protective.

  • Low-density lipoproteins (LDL), which can penetrate the arterial wall and deposit cholesterol within the artery, thus contributing to heart disease.

  • Very-low-density lipoproteins (VLDL), which are similar to LDLs, but can more easily penetrate the artery wall.
  • Intermediate-density lipoproteins. Like VLDLs, these also carry triglycerides and cholesterol.

  • Chylomicrons, which carry only a small percentage of cholesterol. Chylomicrons are mostly rich in another type of fat called triglycerides.

Many studies have shown that high levels of LDLs, IDLs and VLDLs are associated with increased risk of heart attack because these lipoproteins actually harm arteries. Conversely, higher levels of HDLs protect against heart attack because these lipoproteins remove potentially dangerous cholesterol from the blood stream. Thus, modern cholesterol management tends to focus on reducing LDLs while increasing HDLs. The National Cholesterol Education Program classifies cholesterol levels as follows (all measurements are in milligrams per deciliter):

  • Total cholesterol levels less than 200 are desirable.

  • Total cholesterol levels between 200 and 239 are borderline-high.

  • Total cholesterol levels that are 240 or higher are high.

  • HDL levels of less than 40 for men and 50 for women are considered low, and levels of 60 or more are considered protective against heart disease.

  • HDL levels should be 40 or above (the American College of Cardiology recommends levels of 45 or above for women).

  • LDL levels should optimally be less than 100 (levels greater than 129 are considered borderline-high, and levels greater than 159 are considered high). Among some patients, physicians might aim for an even lower LDL target of 70.

Regular cholesterol screenings are important. The NCEP recommends that males and females 20 years of age and older have a cholesterol test every five years. Regular cholesterol screenings are particularly important for people who have risk factors such as diabetes, obesity or a family history of cardiovascular disease. Such higher-risk individuals, and people over age 65, may be screened more frequently.

In the event of high cholesterol or triglyceride levels, physicians may recommend lifestyle modifications along with cholesterol-lowering medications.

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Review Date: 03-27-2007

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