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.
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 arteriescoronary heart disease (CHD)early death from heart diseaseheart attackstroke
A cholesterol test may also be ordered to evaluate disorders of the kidney, liver, or thyroid gland.
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 After the needle is withdrawn, the puncture site is covered for a short time to prevent bleeding.
A cholesterol test is generally done after the individual has fasted overnight.
Total cholesterol results are evaluated as follows: desirable range is less than 200 milligrams per deciliter or mg/dLborderline-high is 200 to 239 mg/dLhigh cholesterol is 240 mg/dL or greater
Abnormally high levels of blood cholesterol may indicate the following: atherosclerosis biliary cirrhosis, which is scarring and blockage of the bile ductsdiet high in cholesterol, saturated fats, calories, or transfats familial hyperlipidemia, a condition in which high blood lipids run in a familyheart attack high stresshypothyroidism, or an underactive thyroid gland lack of exercisenephrotic syndrome, which is a kidney disease resulting in loss of protein in the urineoverweight or obesity uncontrolled diabetes
Abnormally low levels of cholesterol may indicate the following: hyperthyroidism, or an overactive thyroid gland liver diseasemalabsorption, 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.