Definition
- HDL, also known as HDL-C, is produced by the liver and consists of mostly cholesterol, protein, and phospholipid. It carries cholesterol in the bloodstream from the tissues to the liver (reverse cholesterol transport). HDL is termed the "good cholesterol, " � because its levels are inversely related to CHD, and it is an independent risk factor.
- Normal range: see Table 16.19.
� �
TABLE 16 " �19Reference Values for HDL CholesterolView LargeTABLE 16 " �19Reference Values for HDL Cholesterol HDL Cholesterol Level Comments <40 mg/dL Major risk factor for heart disease 40 " �59 mg/dL "The higher, the better " � ≥60 mg/dL Considered protective against heart disease
Use
- Assessment of risk of heart disease and atherosclerosis
- Ordered in combination with total cholesterol, LDL, and triglycerides as a lipid profile
Interpretation
Increased In
- Hyperalphalipoproteinemia
- Regular physical activity or exercise
- Weight loss
- Chronic liver disease
Decreased In
- Uncontrolled diabetes
- Hepatocellular disease
- Chronic renal failure, nephrosis, uremia
- Cholestasis
- Abetalipoproteinemia
- Familial hyper-α-lipoproteinemia (Tangier disease)
- Deficiency of apo A-I and apo C-III
Limitations
- HDL is increased due to moderate ethanol consumption, estrogens, and insulin.
- HDL is decreased due to starvation; stress and recent illness; smoking; obesity and lack of exercise; drugs such as steroids, thiazide diuretics, and beta blockers; hypertriglyceridemia (>1,700 mg/dL); and elevated serum immunoglobulin levels.
- Other factors that may also increase cholesterol include cigarette smoking, age, hypertension, family history of premature heart disease, preexisting heart disease, and DM.
- Low levels of HDL-C (with or without associated co-lipid abnormalities) are seen in Asians than in non-Asians. This is a distinct phenotype associated with increased risk for CHD.
Suggested Reading
1National Institutes of Health, National Heart Lung and Blood Institutes National Cholesterol Education Program. http://www.nhlbi.nih.gov/about/ncep/. Accessed November 18, 2010.