Cholesterol is different from most tests in that it is not used to diagnose or monitor a disease but is used to estimate risk of developing a disease — specifically heart disease. Because high blood cholesterol has been associated with hardening of the arteries, heart disease and a raised risk of death from heart attacks, cholesterol testing is considered a routine part of preventive health care.

Cholesterol testing is recommended as a screening test to be done on all adults at least once every five years. It is frequently done in conjunction with a routine physical exam. It is usually ordered in combination with other tests including HDL, LDL, and triglycerides — often called a lipid profile.

Cholesterol is tested at more frequent intervals (often several times per year) in patients who have been prescribed diet and/or drugs to lower their cholesterol. The test is used to track how well these measures are succeeding in lowering cholesterol to desired levels and in turn lowering the risk of developing heart disease.

In a routine setting where testing is done to screen for risk, the test results are grouped in three categories of risk:

• Desirable : A cholesterol below 200 mg/dL (5.18 mmol/L) is considered desirable and reflects a low risk of heart disease.
• Borderline high: A cholesterol of 200 to 240 mg/dL (5.18 to 6.22 mmol/L) is considered to reflect moderate risk. Your doctor may decide to order a lipid profile to see if your high cholesterol is bad cholesterol (high LDL) or good cholesterol (high HDL). Depending on the results of the lipid profile (and any other risk factors you may have) your doctor will decide what to do.
• High Risk: A cholesterol above 240 mg/dL (6.22 mmol/L) is considered high risk. Your doctor may order a lipid profile (as well as other tests) to try to determine the cause of your high cholesterol. Once the cause is known, an appropriate treatment will be prescribed.

In a treatment setting, testing is used to see how much cholesterol is decreasing as a result of treatment. The goal for the amount of change or the final (target) value will be set by your doctor. The target value is usually based on LDL.

Cholesterol should be measured when a person is healthy. Blood cholesterol is temporarily low during acute illness, immediately following a heart attack, or during stress (like from surgery or an accident). You should wait at least 6 weeks after any illness to have cholesterol measured.

There is some debate about whether very low cholesterol is bad. Low cholesterol (less than 100 mg/dL (2.59 mmol/L)) is often seen when there is an existing problem like malnutrition, liver disease, or cancer. However there is no evidence that low cholesterol causes any of these problems.

Cholesterol is high during pregnancy. Women should wait at least six weeks after the baby is born to have cholesterol measured.

Some drugs that are known to increase cholesterol levels include anabolic steroids, beta blockers, epinephrine, oral contraceptives, and vitamin D.