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Cholesterol and Triglycerides Tests

Test Overview

The cardiovascular system

Cholesterol and triglyceride tests are blood tests that measure the total amount of fatty substances (cholesterol and triglycerides) in the blood.

Cholesterol travels through the blood attached to a protein. This cholesterol-protein package is called a lipoprotein. Lipoprotein analysis (lipoprotein profile or lipid profile) measures blood levels of total cholesterol, LDL cholesterol, HDL cholesterol, and triglycerides.

  • Cholesterol. The body uses cholesterol to help build cells and produce hormones. Too much cholesterol in the blood can build up inside arteries, forming what is known as plaque. Large amounts of plaque increase your chances of having a heart attack or stroke.
  • HDL (high-density lipoprotein) helps remove fat from the body by binding with it in the bloodstream and carrying it back to the liver for disposal. It is sometimes called "good" cholesterol. A high level of HDL is linked with a lower risk of heart disease.
  • LDL (low-density lipoprotein) carries mostly fat and only a small amount of protein from the liver to other parts of the body. A certain level of LDL in your blood is normal and healthy because LDL moves cholesterol to the parts of your body that need it. But it is sometimes called "bad cholesterol" because a high level may increase your chances of developing heart disease.
  • VLDL: (very low-density lipoprotein) contains very little protein. The main purpose of VLDL is to distribute the triglyceride produced by your liver. A high VLDL cholesterol level can cause the buildup of cholesterol in your arteries and increases your risk of heart disease and stroke.
  • Triglycerides are a type of fat the body uses to store energy and give energy to muscles. Only small amounts are found in the blood. Having a high triglyceride level along with a high LDL cholesterol may increase your chances of having heart disease more than having only a high LDL cholesterol level.

Why It Is Done

Cholesterol and triglyceride testing is done:

  • As part of a routine physical exam to screen for a lipid disorder.
  • To check your response to medicines used to treat lipid disorders.
  • To help find your risk of having heart and blood flow problems, including heart attack and stroke.
  • If you have unusual symptoms, such as yellow fatty deposits in the skin (xanthomas), which may be caused by a rare genetic disease that causes very high cholesterol levels.

Cholesterol and triglyceride screening

Talk to your doctor about when you should get a cholesterol test.

Some health organizations recommend that everyone ages 20 to 79 be checked every 4 to 6 years for the risk of heart attack and stroke, which includes a cholesterol test.1 Other organizations recommend cholesterol tests based on age and risk factors for heart disease.2

For more information, see When to Have a Cholesterol Test.

How To Prepare

Preparation may depend on the type of test you are having. You may or may not have to fast.

  • If your doctor tells you to fast before your test, do not eat or drink anything except water for 9 to 12 hours before having your blood drawn. Usually, you are allowed to take your medicines with water the morning of the test. Fasting is not always necessary, but it may be recommended.
  • Do not eat high-fat foods the night before the test.
  • Do not drink alcohol or exercise strenuously before the test.

Many medicines may affect the results of this test. Be sure to tell your doctor about all the nonprescription and prescription medicines and herbs or natural substances you take.

Tell your doctor if you have had a test such as a thyroid or bone scan that uses a radioactive substance within the last 7 days.

Talk to your doctor about any concerns you have regarding the need for the test, its risks, how it will be done, or what the results will mean. To help you understand the importance of this test, fill out the medical test information formmedical test information form(What is a PDF document?).

How It Is Done

The health professional taking a sample of your blood will:

  • Wrap an elastic band around your upper arm to stop the flow of blood. This makes the veins below the band larger so it is easier to put a needle into the vein.
  • Clean the needle site with alcohol.
  • Put the needle into the vein. More than one needle stick may be needed.
  • Attach a tube to the needle to fill it with blood.
  • Remove the band from your arm when enough blood is collected.
  • Put a gauze pad or cotton ball over the needle site as the needle is removed.
  • Put pressure on the site and then put on a bandage.

How It Feels

The blood sample is taken from a vein in your arm. An elastic band is wrapped around your upper arm. It may feel tight. You may feel nothing at all from the needle, or you may feel a quick sting or pinch.

Risks

There is very little chance of a problem from having a blood sample taken from a vein.

  • You may get a small bruise at the site. You can lower the chance of bruising by keeping pressure on the site for several minutes.
  • In rare cases, the vein may become swollen after the blood sample is taken. This problem is called phlebitis. A warm compress can be used several times a day to treat this.
  • Ongoing bleeding can be a problem for people with bleeding disorders. Aspirin, warfarin (Coumadin), and other blood-thinning medicines can make bleeding more likely. If you have bleeding or clotting problems, or if you take blood-thinning medicine, tell your health professional before your blood sample is taken.

Results

Cholesterol and triglyceride tests are blood tests that measure the total amount of fatty substances (cholesterol and triglycerides) in the blood.

Results are usually available within 24 hours.

What do your cholesterol numbers mean?

Your cholesterol levels can help your doctor find out your risk for having a heart attack or stroke.

But it's not just about your cholesterol. Your doctor uses your cholesterol levels plus other things to calculate your risk. These include:

  • Your blood pressure.
  • Whether or not you have diabetes.
  • Your age, sex, and race.
  • Whether or not you smoke.

You and your doctor can talk about whether you need to lower your risk and what treatment is best for you.

If your LDL cholesterol is 190 milligrams per deciliter (mg/dL) or more, it might mean that you have a familial lipid disorder.

For children and teens, test results are slightly different than for adults. For more information, see Cholesterol in Children and Teens.

What Affects the Test

Many conditions can affect cholesterol and triglyceride levels. Your doctor will talk with you about any abnormal results that may be related to your other health problems.

Reasons you may not be able to have the test or why the results may not be helpful include:

  • Medicines, such as diuretics, corticosteroids, male sex hormones (androgens), tranquilizers, estrogen, birth control pills, antibiotics, and niacin (vitamin B3).
  • Physical stress, such as infection, heart attack, surgery.
  • Eating 9 to 12 hours before the test.
  • Other conditions, such as hypothyroidism, diabetes, or kidney or liver disease.
  • Alcohol or drug abuse or withdrawal.
  • Liver disease (such as cirrhosis or hepatitis), malnutrition, or hyperthyroidism.
  • Pregnancy. Values are the highest during the third trimester and usually return to the prepregnancy levels after delivery of the baby.

What To Think About

  • Chylomicrons are another type of lipoprotein that are measured in a different test. Chylomicrons are in the blood and carry fat from your intestine to your liver. They carry triglycerides to your muscles for immediate use. Or they carry triglycerides to fat tissue for storage.
  • Cholesterol screening is often available in supermarkets, pharmacies, shopping malls, and other public places. Home cholesterol testing kits also are available. The results of tests done outside a doctor's office or lab may not be accurate. If you have cholesterol screening done outside your doctor's office, talk with your doctor about the accuracy of the results.

References

Citations

  1. Goff DC Jr, et al. (2013). 2013 ACC/AHA guideline on the assessment of cardiovascular risk: A report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines. Circulation, published online November 12, 2013. DOI: 10.1161/01.cir.0000437741.48606.98. Accessed November 22, 2013.
  2. U.S. Preventive Services Task Force (2008). Screening for lipid disorders in adults. Available online: http://www.uspreventiveservicestaskforce.org/uspstf/uspschol.htm.

Other Works Consulted

  • Chernecky CC, Berger BJ (2013). Laboratory Tests and Diagnostic Procedures, 6th ed. St. Louis: Saunders.
  • Fischbach FT, Dunning MB III, eds. (2009). Manual of Laboratory and Diagnostic Tests, 8th ed. Philadelphia: Lippincott Williams and Wilkins.
  • Goff DC Jr, et al. (2013). 2013 ACC/AHA guideline on the assessment of cardiovascular risk: A report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines. Circulation, published online November 12, 2013. DOI: 10.1161/01.cir.0000437741.48606.98. Accessed November 22, 2013.
  • Miller M, et al. (2011). Triglycerides and cardiovascular disease: A scientific statement from the American Heart Association. Circulation, 123(20): 2292–2333.
  • Stone NJ, et al. (2013). 2013 ACC/AHA guideline on the treatment of blood cholesterol to reduce atherosclerotic cardiovascular risk in adults: A report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines. Circulation, published online November 12, 2013. DOI: 10.1161/01.cir.0000437738.63853.7a. Accessed November 18, 2013.

Credits

By Healthwise Staff
E. Gregory Thompson, MD - Internal Medicine
Rakesh K. Pai, MD, FACC - Cardiology, Electrophysiology
Last Revised December 4, 2013

This information does not replace the advice of a doctor. Healthwise, Incorporated disclaims any warranty or liability for your use of this information. Your use of this information means that you agree to the Terms of Use. How this information was developed to help you make better health decisions.

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