Hdl

Alternate Names
high-density lipoprotein
good cholesterol

Definition of Hdl

An HDL test measures the level of high-density lipoprotein (HDL) in the blood. HDL is known as "good" or "healthy" cholesterol because higher levels of it correlate with lower risks of heart disease and stroke. This is probably because HDL transports unhealthy fats out of the circulation to the liver for processing. The HDL test is generally done along with a total cholesterol, triglycerides, and an LDL test, as part of a lipid profile test.

Who is a candidate for the procedure?

An HDL 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.

Low HDL levels increase a person's risk for the following:

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

How is the test performed?

A blood sample needs to be taken 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 After the needle is withdrawn, the puncture site is covered for a short time to prevent bleeding.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?

An HDL test is generally done after the individual has fasted overnight.

What do the test results mean?

A low HDL level is one that is less than 40 milligrams per deciliter, or mg/dL. Low HDL increases a person's risk for coronary heart disease (CHD). A high HDL is 60 mg/dL or above. High HDL lowers the risk of CHD.