What is a cholesterol test?

A cholesterol test is a simple blood test that measures the amount of cholesterol and other fatty substances (triglycerides) in your blood. Cholesterol and other fats can build up in your blood vessels, especially your arteries. Over time the buildup can form plaque, which can narrow and harden the arteries. Plaque in a blood vessel causes atherosclerosis, which can slow blood flowing through the vessels. Over time this plaque can clog arteries:

  • If the coronary arteries (in your heart) become blocked, it can cause a heart attack.
  • If the carotid arteries (in your neck) become blocked, it can cause a stroke.

Some cholesterol test results are important in revealing if you are at risk for these health problems. The test overall looks at cholesterol levels as well as triglyceride levels. It also looks at two specific types of cholesterol:

  • LDL or low density lipoprotein (bad cholesterol)
  • HDL or high density cholesterol (good cholesterol)

Cholesterol is measured in milligrams per deciliter of blood, or mg/dL. The goal for each level is as follows:

  • Total cholesterol lower than 200 mg/dL
  • LDL lower than 100 mg/dL
  • HDL 40 mg/dL or higher
  • Triglycerides lower than 150 mg/dL

However, only your doctor can tell you what level of cholesterol is "high" for you. Your doctor considers your risk factors when making that decision. For example, if you have no family history of heart disease, an LDL level of 160 mg/dL may be high. For someone with a strong family history of heart disease, an LDL level of 130 mg/dL or lower may be high.

What can I expect?

When you have a cholesterol test, you are usually told to fast (no food or beverages, expect water) for 12 hours before your blood is drawn. The technician inserts a needle into your arm, usually at the bend of your elbow. A sample of your blood flows into a small tube, which is sent to the lab to be studied.