Screening for disease refers to the testing that is performed routinely to test patients for a condition, even though they have not yet developed any signs or symptoms of an illness.
Patients with hypercholesterolemia or a raised cholesterol level often do not show any signs or symptoms until atherosclerosis eventually leads to a heart attack or stroke. The routine screening of cholesterol levels is therefore recommended in people identified as being at risk of cardiovascular disease. This risk can be reduced by detecting the raised cholesterol level early and applying early intervention.
Cholesterol screening involves blood tests to check the level of total cholesterol, “bad” cholesterol (low-density lipoproteins [LDLs] and triglycerides), and “good” cholesterol (high-density lipoproteins [HDLs]). The ratio of total cholesterol to HDL is also assessed, and ideally this should be below 4.
In the United States, this routine testing is recommended for all men aged 35 to 65 years and all women aged 45 to 65 years. There is no clear evidence that routine screening for a high blood cholesterol benefits healthy men and women after 65 years of age.
In the presence of other risk factors for coronary heart disease such as diabetes or high blood pressure, screening is recommended for men aged 20 to 35 years and women aged 20 to 45 years. Once patients have initiated statin therapy, however, routine screening is of little benefit, apart from in terms of monitoring compliance to therapy.
Patients are asked not to eat for 10 to 12 hours before a blood sample is taken, as undigested food can interfere with the blood test results. Hypercholesterolemia is indicated in cases of raised LDL or triglycerides or if the HDL level is lower than usual.
Before deciding whether a patient is at low, moderate or high risk of cardiovascular disease, other risk factors are also taken into consideration such as body mass index, family history, ethnicity, gender and the presence of health conditions such as diabetes and high blood pressure.