Elevated Cholesterol

Cholesterol is a sterol (steroid alcohol) that is essential in cell membrane, steroid hormone, and bile synthesis. Cholesterol is transported via lipoproteins. Obesity is a risk factor for hypercholesterolemia (elevated cholesterol). Hypercholesterolemia increases the risk of atherosclerosis, which is the main cause of cardiovascular disease and stroke. While there is no strong evidence that targeting obesity improves coronary heart disease (CHD) outcome, exercise, diet, and lifestyle modifications effectively treat hypercholesterolemia.

Low-density lipoproteins (LDL) carry cholesterol absorbed by the gut or produced by the liver to the tissues. Excess LDL can lead to vascular damage including atherosclerosis, thrombi, and emboli that can cause stroke or death. LDL levels increase due to increased saturated fat intake or hereditary conditions. High-density lipoproteins (HDL) remove excess cholesterol from the blood. Increased HDL levels protect against CHD. Hypercholesterolemia allows damaging reactions with free cholesterol to occur within vessel walls. Excess LDL forms atheromas and can be taken up by white blood cells, causing them to form foam cells, leading to further damage. Oxidizing reactions, atheromas and foam cells increase blood pressure, the formation of thrombi and emboli, and the risk of atherosclerosis.

[Page 225]Cholesterol screening is recommended for men older than 35 years and women older than 45 years. If other risk factors such as diabetes, high blood pressure, smoking, or a family history of premature cardiovascular disease exist, screening should begin after 20 years of age.

Fasting measurement of total cholesterol, triglycerides, and HDL allows LDL calculation. Optimally, total cholesterol should be under 200 mg/dL, LDL should be under 100 mg/dL, HDL should be over 41 mg/dL, triglycerides should be under 150 mg/dL, and the total cholesterol to HDL ratio should be under 4. The Framingham score considers total cholesterol, HDL, smoking history, blood pressure, and age to predict the risk of developing coronary heart disease.

Treatment of hypercholesterolemia involves lifestyle modifications including diet and exercise. Several classes of medication, including statins, bile-acid–binding resins, fibric acid derivatives, cholesterol absorption inhibitors, and niacin, can be used if lifestyle modifications are unsuccessful. Only statins, which reduce the rate of de novo cholesterol synthesis, have been shown to reduce overall mortality due to hypercholesterolemia complications.