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High Cholesterol and Dyslipidemia

Dyslipidemias may be manifested by elevation of the serum total cholesterol, low-density lipoprotein (LDL) cholesterol and triglycerides, and a decrease in the high-density lipoprotein (HDL) cholesterol. Elevated serum cholesterol levels are associated with the development of coronary heart disease, and aggressive cholesterol reduction results in increased rates of plaque regression.

Diagnosis and classification

Secondary causes of dyslipidemia include hypothyroidism and a genetic predisposition, such as autosomal dominant familial hypercholesterolemia. Triglyceride elevation may occur in association with diabetes mellitus, alcoholism, obesity.

The National Cholesterol Education Program (NCEP) guidelines are based on clinical cut points that indicate relative risk for coronary heart disease. Total cholesterol and HDL cholesterol levels be measured every five years beginning at age 20 in patients who do not have coronary heart disease or other atherosclerotic disease.

Coronary Heart Disease Risk Based on Risk Factors Other Than the LDL Level

Positive risk factors

Male $45 years

Female $55 years or postmenopausal without estrogen replacement therapy

Family history of premature coronary heart disease (definite myocardial infarction or sudden death before age 55 in father or other male first-degree relative or before age 65 in mother or other female first-degree relative)

Current cigarette smoking

Hypertension (blood pressure $140/90 mm Hg or patient is receiving antihypertensive drug therapy)

HDL cholesterol level <35 mg/dL (<0.90 mmol/L)

Diabetes mellitus

Negative risk factor*

High HDL cholesterol level ($60 mg/dL [$1.60 mmol/L])

*--Subtract one positive risk factor if negative risk factor is present.

The LDL cholesterol level can be calculated by using the Friedwald formula (mg/dL): LDL=total cholesterol - HDL - (triglyceride/5)

Management

The target LDL cholesterol value in patients with coronary heart disease or other atherosclerotic disease is 100 mg/dL or lower. If the LDL level does not exceed 100 mg/dL in a patient with coronary heart disease, the patient should begin.

The NCEP guidelines recommend that patients at higher risk of coronary heart disease receive more intensive interventions.

Risk Classification of Hypercholesterolemia in Patients Without Coronary Heart Disease
Classification	Total cholesterol level	LDL cholesterol level	HDL cholesterol level
Desirable	200 mg/dL	<130 mg/dL	$60 mg/dL
Borderline high risk	200 to 239 mg/dL	130 to 159 mg/dL	35 to 59 mg/dL
High risk	$240 mg/dL	$160 mg/dL	<35 mg/dL

Lifestyle modifications

The NCEP guidelines recommend dietary modification, exercise and weight control as the foundation of treatment.

Exercise and weight reduction lowers total cholesterol and its LDL and VLDL fractions, lowers triglycerides and raises HDL cholesterol. Most patients benefit from aerobic exercise that targets large muscle groups, performed for 30 minutes lowers total cholesterol and its LDL and VLDL fractions, lowers triglycerides and raises HDL cholesterol. Most patients benefit from aerobic exercise that targets large muscle groups, performed for 30 minutes.

Step I and step II diets

Dietary therapy should be initiated in patients who have borderline-high LDL cholesterol levels (130 to 159 mg/dL) and two or more risk factors for coronary heart disease and in patients who have LDL levels of 160 mg/dL or greater.

Step I diet limits calories derived from saturated fats to 8 to 10 percent of total calories and cholesterol to less than 300 mg/day. limits calories derived from saturated fats to 8 to 10 percent of total calories and cholesterol to less than 300 mg/day.

Step II diet further restricts calories from saturated fats to less than 7 percent of total calories and restricts cholesterol intake to less than 200 mg/day. further restricts calories from saturated fats to less than 7 percent of total calories and restricts cholesterol intake to less than 200 mg/day.

In primary prevention of coronary heart disease (without evidence of coronary heart disease), dietary therapy.

Drug therapy

Because dietary modification rarely reduces LDL cholesterol levels by more than 10 to 20 percent, the NCEP guidelines.

A patient with a very high LDL cholesterol level may need to start drug therapy sooner, because it is unlikely that a patient with an LDL level of 130 mg/dL or greater will be able to achieve the goal of 100 mg/dL with diet alone. may need to start drug therapy sooner, because it is unlikely that a patient with an LDL level of 130 mg/dL or greater will be able to achieve the goal of 100 mg/dL with diet alone.

HMG-CoA reductase inhibitors are the drugs of choice In most patients with hypercholesterolemia because they reduce LDL cholesterol most effectively. Gemfibrozil (Lopid) or nicotinic acid may be better choices in patients with significant hypertriglyceridemia. are the drugs of choice In most patients with hypercholesterolemia because they reduce LDL cholesterol most effectively. Gemfibrozil (Lopid) or nicotinic acid may be better choices in patients with significant hypertriglyceridemia.