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A cholesterol test measures the total amount of cholesterol in the blood. It is generally done along with blood tests that measure a person's triglycerides, HDL cholesterol, that is, "good" or "healthy" cholesterol and LDL cholesterol, that is, "bad" or "lethal" cholesterol. Cholesterol is a form of lipid (fat) in the body that is used for many body processes.

Who is a candidate for the procedure?

A cholesterol test may be ordered to evaluate a person's risk for various conditions.

Adults 20 years or over should be tested every five years for cholesterol, LDL, HDL, and triglycerides.

High cholesterol levels increase a person's risk for the following conditions:

• arteriosclerosis, that is, narrowing of the arteries
• coronary heart disease (CHD)
• early death from heart disease
• heart attack
• stroke

A cholesterol test may also be ordered to evaluate disorders of the kidney, liver, or thyroid gland.

How is the test performed?

A blood sample needs to be taken in order to measure the level of blood cholesterol. The blood is usually drawn from a vein in the forearm or the hand. First, the skin over the vein is cleaned with an antiseptic. Next, a strong rubber tube called a tourniquet is wrapped around the upper arm. This enlarges the veins in the lower arm by restricting blood flow through them. A very thin needle is gently inserted into a vein and the tourniquet is removed. Blood flows from the vein through the needle and is collected in a syringe or vial. The sample is sent to the lab to be analyzed. After the needle is withdrawn, the puncture site is covered for a short time to prevent bleeding.

What is involved in preparation for the test?

A cholesterol test is generally done after the individual has fasted overnight.

What do the test results mean?

• desirable range is less than 200 milligrams per deciliter or mg/dL
• borderline-high is 200 to 239 mg/dL
• high cholesterol is 240 mg/dL or greater

• atherosclerosis
• biliary cirrhosis, which is scarring and blockage of the bile ducts
• diet high in cholesterol, saturated fats, calories, or transfats
• familial hyperlipidemia, a condition in which high blood lipids run in a family
• heart attack
• high stress
• hypothyroidism, or an underactive thyroid gland
• lack of exercise
• nephrotic syndrome, which is a kidney disease resulting in loss of protein in the urine
• overweight or obesity
• uncontrolled diabetes

• hyperthyroidism, or an overactive thyroid gland
• liver disease
• malabsorption, or inadequate absorption of nutrients from the intestines
• malnutrition

A person's LDL level is also extremely important in evaluating his or her risk for CHD.