HDL-C is a class of lipoproteins produced by the liver and intestines. HDL is composed of phospholipids and one or two apolipoproteins. It plays a role in the metabolism of the other lipoproteins and in cholesterol transport from peripheral tissues to the liver. LDL and HDL may combine to maintain cellular cholesterol balance through the mechanism of LDL moving cholesterol into the arteries and HDL removing it from the arteries. Decreased HDL levels are atherogenic, whereas elevated HDL levels protect against arthrosclerosis by removing cholesterol from vessel walls and transporting it to the liver where it is removed from the body. This is known as the “reverse cholesterol transport pathway.” There is a strong relationship between HDL-C and CAD.
HDL-C, the good cholesterol, is used to assess CAD risk and monitor persons with known low HDL levels. HDL-C levels are inversely proportional to CAD risk and are a primary independent risk factor. When a slightly increased cholesterol is due to high HDL, therapy is not indicated.
Men: 35–65 mg/dL or 0.91–1.68 mmol/L
Women: 35–80 mg/dL or 0.91–2.07 mmol/L
<25 mg/dL or <0.65 mmol/L of HDL: CAD risk at dangerous level: 2 times the risk
26–35 mg/dL or 0.67–0.91 mmol/L of HDL: high CAD risk: 1.5 times the risk
36–44 mg/dL or 0.93–1.14 mmol/L of HDL: moderate CAD risk: 1.2 times the risk
45–59 mg/dL or 1.16–1.53 mmol/L of HDL: average CAD risk
60–74 mg/dL or 1.55–1.92 mmol/L of HDL: below average CAD risk
>75 mg/dL or >1.94 mmol/L of HDL: no risk (associated with longevity)
The cholesterol-to-HDL ratio provides more information than does either value alone. The higher the cholesterol-to-HDL ratio, the greater the risk for developing atherosclerosis. This ratio may be reported with total cholesterol values, along with the percentage of HDL-C.
Obtain a 5-mL venous blood sample (red-topped tube). Fasting is necessary. The HDL is precipitated out from the total cholesterol for analysis.
Calculate a cholesterol-to-HDL-C ratio from these values.
Procedural Alert
Cholesterol and HDL-C levels should not be measured immediately after MI. A 3-months wait is suggested
Increased HDL-C values occur in the following conditions:
Familial hyper-α-lipoproteinemia (HDL excess)
Chronic liver disease (cirrhosis, alcoholism, hepatitis)
Long-term aerobic or vigorous exercise
Decreased HDL-C values are associated with increased risk for CAD and premature CAD and occur in the following conditions:
Familial hypo-α-lipoproteinemia (Tangier disease), apolipoprotein C-III deficiency
α-β-lipoproteinemia
Hypertriglyceridemia (familial)
Poorly controlled diabetes
Hepatocellular diseases
Cholestasis
CKD, uremia, nephrotic syndrome
In the United States, 3% of men have low HDL levels for unknown reasons, even though cholesterol and triglyceride values are normal, and they are at risk for premature CAD.
Pretest Patient Care
Explain test purpose. An 8- to 12-hour fast is recommended. Alcohol should not be consumed for at least 24 hours before test.
Ensure that patient is on a stable diet for 3 weeks.
If possible, withhold all medication for at least 24 hours before testing. Check with the healthcare provider.
Encourage relaxation.
Follow guidelines in Chapter 1 for safe, effective, informed pretest care.
Posttest Patient Care
Review test results; report and record findings. Modify the nursing care plan as needed.
Low HDL levels can be raised by diet management, exercise, weight loss, and smoking cessation. Many resources are available through the American Heart Association and other organizations.
Drug therapy may be necessary if other methods fail to raise HDL levels.
Follow guidelines in Chapter 1 for safe, effective, informed posttest care.
Increased HDL level is associated with estrogen therapy, moderate intake of alcohol and other drugs (especially androgenic and related steroids), and insulin therapy.
Decreased HDL levels are associated with the following:
Certain drugs such as steroids, antihypertensive agents, diuretic agents, β-blockers, triglycerides, and thiazides
Stress and recent illness
Starvation and anorexia
Obesity, lack of exercise
Smoking
Hypertriglyceridemia (>400 mg/dL or >10.36 mmol/L) (retest making sure the patient is properly fasting)