Recommendations for cholesterol screening and treatment have been provided by the National Institutes of Health and are summarized in the National Cholesterol Education Program (NCEP). The guidelines recommend that all adults have their cholesterol levels checked at least once every 5 years. Patients with coronary heart disease or other forms of atherosclerosis are at the highest risk for heart attack and stroke. These patients may benefit the most from cholesterol-reduction therapy and should have a full lipid profile annually.
The NCEP recommends checking the total cholesterol and HDL cholesterol levels. However, since many cholesterol-management decisions are based primarily on LDL cholesterol levels, a full lipid profile (i.e., total cholesterol, HDL cholesterol, LDL cholesterol, and triglycerides) may be recommended. Triglyceride and LDL levels are affected by eating, so it is necessary to fast for 12 hours before testing.
NCEP recommendations are based on the LDL cholesterol level because this level correlates closely with risk for heart attack and death, and because treatment of the LDL level has been the focus of recent studies.
There is no formula to determine what cholesterol level is considered "safe" and what cholesterol level requires treatment. General recommendations are based on ongoing research regarding future risk for heart attack. The reason for this is that a person without risk factors for coronary heart disease often can tolerate somewhat elevated cholesterol levels. In a person with established coronary heart disease, the risk for heart attack (or subsequent heart attack) and death is much higher, so even mildly elevated cholesterol levels must be treated aggressively.
Many physicians recommend that patients without known atherosclerosis should strive to lower their LDL cholesterol level below 160-190 mg/dL. In patients with risk factors for coronary heart disease (e.g., diabetes, high blood pressure, cigarette smoking, history of premature heart disease in parents or siblings), a level below 130 mg/dL may be considered more desirable. Patients with known atherosclerosis and LDL levels above 100-130 mg/dL are treated to lower their cholesterol to 70 mg/dL.