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 HDL, also known as the good carrier for cholesterol and LDL, or the so-called bad carrier for cholesterol. Cholesterol is a waxy substance 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:
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 After the needle is withdrawn, the puncture site is covered for a short time to prevent bleeding.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:
Abnormally high levels of blood cholesterol may indicate the following:
Abnormally low levels of cholesterol may indicate the following:
A person's LDL level is also extremely important in evaluating his or her risk for CHD.
Author:David T. Moran, MD
Editor:Ballenberg, Sally, BS
Reviewer:Eileen McLaughlin, RN, BSN