HA has no clear-cut definition. An arbitrary cutoff is the 10th percentile of HDL cholesterol levels. A more practical definition derives from the theoretical cardioprotective role of HDL. The US National Cholesterol Education Program (NCEP) Adult Treatment Panel III (ATP III) redefined the HDL cholesterol level that constitutes a formal coronary heart disease (CHD) risk factor. The level was raised from 35 mg/dL to 40 mg/dL for men and women. A prospective analysis by Mora et al investigated the link between cholesterol and cardiovascular events in women and found baseline HDL-C level was consistently and inversely associated with incident coronary and CVD events across a range of LDL-C values.
For the metabolic syndrome in which multiple mild abnormalities in lipids, waist size (abdominal circumference), blood pressure, and blood sugar increase the risk of CHD, the designated HDL cholesterol levels that contribute to the syndrome are sex-specific. For men, a high-risk HDL cholesterol level is still less than 40 mg/dL, but for women, the high-risk HDL cholesterol level is less than 50 mg/dL.
A low HDL cholesterol level is thought to accelerate the development ofatherosclerosis because of impaired reverse cholesterol transport and possibly because of the absence of other protective effects of HDL, such as decreased oxidation of other lipoproteins.
The common, mild forms of HA have no characteristic physical findings, but patients may have premature coronary heart or peripheral vascular disease, as well as a family history of low HDL cholesterol levels and premature CHD.
Therapy to raise the concentration of HDL cholesterol includes weight loss, smoking cessation, aerobic exercise, and pharmacologic management with niacin and fibrates.
This review addresses the pathogenesis and presenting features of, and the diagnostic tests, therapeutic interventions, and follow-up strategies for, low HDL cholesterol levels.
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