Hyperlipidemia

Department of the Navy
Bureau of Medicine and Surgery

Hyperlipidemia is frequently encountered in routine screening and physical exams. All adults over the age of 20 should have a random total cholesterol blood test. A total cholesterol less than 200 mg/dl is desirable, 201-239 mg/dl is borderline and greater than 240 mg/dl is considered high. Patients with desirable levels should be counseled on prudent diet and risk factor modification to maintain a low risk for cardiovascular disease. Total cholesterol should be measured every 5 years. Patients with a total cholesterol over 200 mg/dl should have a fasting (12-14 hours) total cholesterol, HDL (high density lipoprotein) cholesterol, and triglycerides measured. The LDL (low density lipoprotein) cholesterol in routine measurement is a value calculated as follows: total cholesterol - HDL - (TRIG/5). This is accurate if the triglyceride level is less than 400 mg/dl). A desirable triglyceride level is < 200 mg/dl.

The patient should be screened and questioned for symptoms or history of known coronary artery disease (CAD) (angina, myocardial infarction) and risk factors for CAD (coronary artery disease): smoking, male gender, first degree relatives with CAD under age 55, diabetes mellitus, hypertension (> 140/90 mm Hg), symptoms of peripheral vascular disease (PVD), history of CVA/TIA, obesity (> 30 percent ideal body weight (IBW), and HDL < 35 mg/dl. This information is important for therapeutic decisions. Additionally, secondary and potentially correctable causes of hyperlipidemia should be sought including diabetes mellitus, hypothyroidism, renal failure, nephrotic syndrome, alcohol abuse, and liver disease. Certain drugs (thiazide diuretics, beta blockers, and glucocorticoids) can also elevate cholesterol.

On physical examination, note the blood pressure, peripheral pulses, weight, tendon or eruptive xanthoma, or xanthelasma and abdominal/peripheral bruits. Examine the eyes for findings of diabetes or hypertension. Laboratory studies may include thyroid function studies (including TSH), BUN, creatinine, liver function tests, urinalysis, and fasting blood glucose. Therapy is goal-directed. In the absence of CAD, and with one of the above risk factors for CAD, the patient's target LDL is < 160 mg/dl. With CAD or two or more risk factors the goal LDL is < 130 mg/dl. If the patient has known CAD or PVD (peripheral vascular disease), the ideal LDL should be even lower; 100 to 130 mg/dl.

Therapy centers around diet. The Step One diet (total fat intake < 30 percent of total calories, saturated fats < 10 percent and total cholesterol < 300 mg/day) is prescribed. Numerous references are available to guide both the physician and patient. Emphasize that diet, not medication, is the mainstay of therapy, requiring a permanent lifestyle modification. Sensitive, but persistent, work with the supply officer can help lower dietary fat and cholesterol not only for an individual patient, but also for the whole crew. The services of a registered dietitian, where available, prove invaluable. When the Step One diet is insufficient, and before the addition of medical therapy, dietary consultation (for the more rigid, Step Two, dietary management) is mandatory. Treatment also involves risk factor reduction. Smoking must cease. Regular exercise should be encouraged since this raises HDL and lowers weight and blood pressure. Hypertension should be aggressively treated. Before prescribing an anti-lipid drug, secondary causes of hyperlipidemia should be treated, and if the patient is taking a medication that could cause hyperlipidemia, consideration should be made to changing the drugs, if possible. Retest the lipid panel in 8 to 12 weeks after any therapeutic changes. These steps may allow the patient to achieve his or her target LDL level without additional drugs.

Medications (see table 1) are added to, not substituted for treatment if the above target LDL levels are not met after a 6 month trial of diet and exercise, provided the patient is not high risk. Long-term follow-up is vital, as side effects may be significant (and asymptomatic) and patient motivation may wane. Contact the nearest internal medicine, endocrinology, or cardiology service for assistance in the specifics of evaluation and treatment of hyperlipidemia. Patients who require more than diet and one medication, who have secondary causes not readily evaluated or managed at the GMO level, or who are suspected of having CAD should be referred.

Table 1

Reference

1. National Cholesterol Education Program. (Adult Treatment Panel 11.) Summary of the Second Report of the National Cholesterol Education Program Expert Panel on Detection, Evaluation and Treatment of High Blood Cholesterol in Adults. JAMA 1993; 269:3015-3023.