High Cholesterol: Diagnosis and Treatment

Diagnosis

• The National Cholesterol Education Program (NCEP) recommends routine blood cholesterol assessment every five years beginning at age 20. More frequent screening should be performed for persons who have high total cholesterol, low HDL, or other risk factors for heart disease.
  
  Individuals should fast for at least 12 hours before blood sampling.
  
• Total cholesterol: According to NCEP guidelines, total cholesterol below 200 milligrams (mg) per deciliter (dL) is desirable. A borderline high level is 200 to 239 mg/dL. High cholesterol is defined as greater than 240 mg/dL.
  
  However, some evidence suggests that stricter standards may be appropriate. The risk of cardiac events decreases as total cholesterol levels fall, so many authorities suggest that the goal for total cholesterol should be approximately 150 mg/dL.
• Triglycerides: Normal triglyceride level is less than 150 mg/dL. Borderline is 150 to 199 mg/dL, and high is 200 to 499 mg/dL. Levels of 500 mg/dL or higher are considered very high.
• HDL cholesterol: Concentrations of 60 mg/dL or higher are ideal. In general, an HDL concentration below 40 mg/dL is considered a major risk factor for coronary heart disease. Some experts suggest, however, that HDL concentration should be considered in comparison with total cholesterol. In this way, the HDL value should be at least one-third that for total cholesterol.
• LDL cholesterol: According to the NCEP, LDL cholesterol levels below 100mg/dL are considered ideal. A range of 100 to 129 mg/dL is near optimal. Borderline is 130 to 159 mg/dL. High is 160 to 189 mg/dL. However, increasing evidence supports stricter standards. Many researchers and clinicians believe that 100 mg/dL should be the upper limit for everyone, and some recommend reductions below 70 mg/dL for high-risk individuals.
  
  Studies of hunter-gatherer populations and normal newborn babies have modified the concept of normal cholesterol levels. Normal human LDL cholesterol concentration may be as low as 50 to 70 mg/dL. Coronary heart disease risk decreases as LDL cholesterol concentration decreases, and may reach its lowest level at approximately 40 mg/dL.

Treatment

The mainstay of treatment for hyperlipidemia is dietary and lifestyle modification, followed by drug therapy, as necessary. Dietary steps are discussed in Nutritional Considerations.

• Regular exercise can improve HDL and triglyceride levels, but have little effect on LDL. Low to moderate amounts of physical activity, such as walking, lower triglyceride levels by an average of 10 mg/dL, while raising HDL by an average of 5 mg/dL. More strenuous activity may have greater effects.
• HMG-CoA reductase inhibitors (statins) decrease cholesterol production in the liver, and are the first-line drugs in the treatment of elevated LDL cholesterol. Statins also have important effects on cardiovascular risk, and may be even be recommended for high-risk individuals with normal cholesterol levels.
  
  However, potential side effects include muscle pain and liver disorders. Further, some statins may also lower HDL.
  
• Bile acid sequestrants (e.g., cholestyramine and colestipol) are second-line agents for the treatment of elevated LDL cholesterol. They decrease the absorption of cholesterol from the gut. These medications can produce gastrointestinal discomfort, constipation, and impaired absorption of other drugs.
• Fibrates (e.g., gemfibrozil and fenofibrate) are used as first-line treatment for elevated triglyceride levels and may be used in combination with the above drugs. Potential side effects include gallstones, indigestion, and muscle disorders.
• Nicotinic acid (niacin) is a second-line therapy for all lipid disorders. Niacin is often combined with statins, but is also effective as a single agent. Side effects include skin itching or burning, gastrointestinal discomfort, liver damage, high blood sugar, and gout.
• Ezetimibe and colesevelam also decrease absorption of cholesterol from the gut, and have emerged as a favored second-line therapy due to their effectiveness, safety, and lack of side effects. They lower LDL and often raise HDL, and are particularly effective when combined with statins.