At a Glance
Why Get Tested?
To screen for risk of developing heart disease
When to Get Tested?
Adults should be tested once every five years or more frequently if being treated for high cholesterol or have one or more risk factors for heart disease. Children and adolescents with risk factors should also have their cholesterol level checked.
A blood sample drawn from a vein in the arm or a fingerstick
Test Preparation Needed?
If you are having this test performed as part of the Lipid profile, you will need to fast for 9-12 hours before the sample is collected; only water is permitted.
The Test Sample
What is being tested?
Cholesterol is a substance (a steroid) that is essential for life. It forms the membranes for cells in all organs and tissues in your body. It is used to make hormones that are essential for development, growth, and reproduction. It forms bile acids that are needed to absorb nutrients from food. A small amount of your body’s cholesterol circulates in the blood in complex particles called lipoproteins. These lipoproteins include some particles that carry excess cholesterol away for disposal (see HDL-C, good cholesterol) and some particles that deposit cholesterol in tissues and organs (see LDL-C, bad cholesterol). The test for cholesterol measures total cholesterol (good and bad) that is carried in the blood by lipoproteins.
Your body produces the cholesterol needed to work properly, but the source for some cholesterol is your diet. If you have an inherited predisposition for high cholesterol levels or if you eat too much of the foods that are high in cholesterol, saturated fats, and trans unsaturated fats (trans fats), then levels of cholesterol in your blood may increase and have a negative impact on your health. The extra cholesterol in your blood may be deposited in plaques on the walls of blood vessels. Plaques can narrow or eventually block the opening of blood vessels, leading to hardening of the arteries (atherosclerosis) and increasing your risk of numerous health problems, including heart disease and stroke.
Monitoring and maintaining healthy levels of cholesterol is important in staying healthy.
How is the sample collected for testing?
Most often, a blood sample is collected from a vein in your arm. Sometimes cholesterol is measured using a drop of blood collected by puncturing the skin on a finger. A fingerstick sample is typically used when cholesterol is being measured on a portable testing device - for example, at a health fair.
NOTE: If undergoing medical tests makes you or someone you care for anxious, embarrassed, or even difficult to manage, you might consider reading one or more of the following articles: Coping with Test Pain, Discomfort, and Anxiety, Tips on Blood Testing, Tips to Help Children through Their Medical Tests, and Tips to Help the Elderly through Their Medical Tests.
Another article, Follow That Sample, provides a glimpse at the collection and processing of a blood sample and throat culture.
Is any test preparation needed to ensure the quality of the sample?
If a cholesterol test is to be performed alone, it is not necessary to fast. However, if it is to be performed as part of a lipid profile, as it often is, then fasting for 9-12 hours before the test will be required; only water is permitted.
Ask a Laboratory Scientist
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NOTE: This article is based on research that utilizes the sources cited here as well as the collective experience of the Lab Tests Online Editorial Review Board. This article is periodically reviewed by the Editorial Board and may be updated as a result of the review. Any new sources cited will be added to the list and distinguished from the original sources used.
Sources Used in Current Review
American Heart Association. How to Get Your Cholesterol Tested. (Updated April 4, 2008) Available online at http://americanheart.org/presenter.jhtml?identifier=541 through http://americanheart.org. Accessed July 2008.
Third Report of the National Cholesterol Education Program (NCEP) Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (Adult Treatment Panel III). May 2001. PDF available for download at http://www.nhlbi.nih.gov/guidelines/cholesterol/atp3full.pdf through http://www.nhlbi.nih.gov. Accessed July 2008.
American Academy of Family Physicians. Cholesterol: What Your Level Means. (Updated October 2007). Available online at http://familydoctor.org/online/famdocen/home/common/heartdisease/risk/029.html through http://familydoctor.org. Accessed July 2008.
Daniels, SR, Greer FR, and the Committee on Nutrition. Lipid screening and cardiovascular health in childhood (clinical report). Jul 2008. Pediatrics 122:198-208.
American Academy of Pediatrics. AAP issues new guidelines on cholesterol screening (press release). 7 Jul 2008. Available online at http://www.aap.org/new/july08lipidscreening.htm through http://www.aap.org. Accessed August 2008.
American Academy of Pediatrics Lipid Screening and Cardiovascular Health in Childhood. Pediatrics Vol. 122 No. 1 July 2008, pp. 198-208. Available online at http://aappolicy.aappublications.org/cgi/content/full/pediatrics;122/1/198 through http://aappolicy.aappublications.org. Accessed September 2008.
Sources Used in Previous Reviews
Thomas, Clayton L., Editor (1997). Taber’s Cyclopedic Medical Dictionary. F.A. Davis Company, Philadelphia, PA [18th Edition].
Pagana, Kathleen D. & Pagana, Timothy J. (2001). Mosby’s Diagnostic and Laboratory Test Reference 5th Edition: Mosby, Inc., Saint Louis, MO.
National Heart, Lung, and Blood Institute of the National Institutes of Health, United States Department of Health and Human Services. Third report of the National Cholesterol Education Program (NCEP) Expert Panel on detection, evaluation, and treatment of high blood pressure in adults (Adult Treatment Panel III). Bethesda, Md. 2001 May. Available online at http://www.nhlbi.nih.gov/guidelines/cholesterol/atp3_rpt.htm