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The Significance of Very High HDL Levels

High-density lipoprotein (HDL) is often referred to as "the good cholesterol." It opposes low-density lipoprotein (LDL), which is contrarily referred to as "the bad cholesterol." For the most part, high levels are believed to be beneficial to health, provided levels are not excessively high. However, there is little consensus in the medical community on what qualifies as "very high" levels of HDL.

  1. Definition of " Very High" HDL Levels

    • According to the U.S. National Cholesterol Education Program Adult Panel Treatment III, high levels of HDL are levels higher than 60 mg/dL. Low levels of HDL are levels lower than 40 mg/dL. Therefore, people with levels in between 40 and 60 are considered to have HDL levels in the normal range. However, there is no established precedent to determine what levels qualify as "very high." Some experts consider levels higher than 80 mg/dL to be "very high," but others contradict this.

    Genetic and Envrionmental Factors

    • Generally, high HDL levels are more common in women than in men. Also, high HDL levels are more common in blacks than in whites. Medical experts have established that genetic factors influence HDL cholesterol levels. However, environmental factors also affect HDL levels. Specifically, chronic alcoholism, treatment with oral estrogen replacement therapy, rigorous aerobic and cardiovascular activity, and treatments involving niacin, statins or fibrates are known to increase HDL. Smoking reduces HDL levels, and cessation of smoking increases HDL levels.

    Low Levels of LDL

    • Very elevated HDL levels are related to low levels of LDL cholesterol and triglyceride (TG). Although the relationship is not apparently clear to experts, there seems to be an association between high HDL levels and low LDL levels. Hence, some experts believe the primary significance of high HDL levels is the tendency of low LDL levels. It is rare for a person to have very elevated levels of HDL and LDL.

    Reduced Risk for Coronary Heart Disease

    • For the most part, very high HDL levels indicate a decreased risk for coronary heart disease (CHD). HDL consists of two major apolipoproteins, apolipoprotein A-I and apolipoprotein A-II. It is the elevated concentration of these two proteins, specifically, which is known to reduce the risk of CHD.

    Atherogenesis

    • Although elevated levels of HDL are largely beneficial, extremely high levels (the definition of which remains unclear) are believed to be atherogenic. Atherogenesis is the deposition of atheromas, lipids and calciums in the lumen of the arteries. The reasons for very high HDL levels' association with atherogenesis are not entirely understood.

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