A 57-year-old woman has experienced episodes of chest pain recently. These episodes have occurred when she has walked only a couple of city blocks, from the courthouse where she works to the fast food place where she eats her usual lunch--a double cheeseburger with order of fries. On examination her height is 165 cm (5' 5") and weight 84 kg (185 lbs), with BMI 31. Her heart rate is 81/min and regular with no murmurs. Her blood pressure is 140/90 mm Hg.
Laboratory findings show:
182 mg/dL (<200 mg/dL)
276 mg/dL (<200 mg/dL)
211 mg/dL (<110 mg/dL)
29 mg/dL (>60 mg/dL)
118 mg/dL (<110 mg/dL)
How do you interpret these findings?
Her BMI is >30. Her triglycerides are "normal" according the range used here, but above 150 mg/dL. The total cholesterol is high and the HDL cholesterol is low. Thus, the profile suggests an increased risk for development of atherosclerosis. She has insulin resistance, though not definitial criteria for diabetes mellitus, shown by the fasting glucose.
What is the probable cause for these findings?
She meets criteria for metabolic syndrome, defined as diabetes or impaired fasting glycemia or impaired glucose tolerance or insulin resistance, plus 2 or more of the following:
Obesity: BMI >30 or waist-to-hip ratio >0.9 (male) or >0.85 (female)
Dyslipidemia: triglycerides > or = 150 mg/dL or HDL cholesterol <35 (male) or <39 (female) mg/dL
Hypertension: blood pressure >140/90 mm Hg
Microalbuminuria: albumin excretion >20 mg/min
There are many possible causes. For a moderate elevation of the cholesterol as seen in this patient, there may not be a specific explanation, or the problem may be multifactorial. Dietary factors may play a role. Much larger elevations in cholesterol may suggest hereditary hypercholesterolemia, in which there are fewer LDL receptors in the heterozygote (with total cholesterol in the 300 - 400 range) and almost no LDL receptors in the homozygote (with total cholesterol exceeding 500).
What can be done to help?
Reducing total fat, reducing cholesterol intake, and increasing exercise can help. For cholesterol levels that remain high, there is drug therapy. Her BMI is 31, placing her at high risk for cardiovascular complications, so weight reduction is indicated.
Is there a medication available to treat this condition?
The "statin" drugs have become popular. They work by inhibiting the hepatic enzyme HMG Co-A reductase. The conversion of HMG-CoA to mevalonate is an early step in the biosynthetic pathway for endogenous cholesterol synthesis.