At a Glance
Why Get Tested?
To help assess the risk of developing heart disease
When to Get Tested?
When other tests, such as a lipid profile, are being performed
A blood sample drawn from a vein in your arm or a fingerstick
Test Preparation Needed?
Overnight fasting is required.
The Test Sample
What is being tested?
Very low-density lipoprotein (VLDL) is one of the four major lipoprotein particles. The other three are high density lipoprotein (HDL), low density lipoprotein (LDL), and chylomicrons. Each particle contains a mixture of cholesterol, triglyceride, and protein, but in varying amounts unique to each type of particle. LDL contains the highest amount of cholesterol. HDL contains the highest amount of protein. VLDL and chylomicrons contain the highest amount of triglyceride.
VLDL particles are released into the blood by the liver and circulate in the bloodstream, ultimately being converted into LDL as they lose triglyceride, having carried it to other parts of the body. According to the National Heart, Lung and Blood Institute's National Cholesterol Education Program Guidelines ATP III, there is growing evidence that VLDL plays an important role in atherogenesis, in which plaques form on the interior walls of arteries, narrowing these passageways and restricting blood flow – and eventually leading to heart disease.
At present there is no simple, direct way of measuring VLDL cholesterol. However, since VLDL-C contains most of the circulating triglyceride (if a person is fasting) and since the composition of the different particles is relatively constant, it is possible to estimate the amount of VLDL-C by dividing the triglyceride value by an appropriate factor. If the triglyceride value is in mg/dL, divide by 5. If the triglyceride value is in mmol/L, divide by 2.2. This estimate is used in most settings. The calculation is not valid, however, when the triglyceride level is greater than 400 mg/dl (4.5 mmol/L) because other lipoproteins are usually present. Triglycerides are routinely measured only when a patient is fasting; otherwise these calculations are invalid.
How is the sample collected for testing?
A blood sample is obtained by inserting a needle into a vein in the arm. Sometimes a drop of blood is collected by puncturing the skin on a fingertip.
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?
Since VLDL-C is usually calculated from the triglyceride level, preparation is the same as for the triglyceride test: fasting for 9 to 12 hours beforehand (only water is permitted) and avoidance of alcohol for 24 hours just before the test.
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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.
MedlinePlus Medical Encyclopedia: VLDL Test. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/003494.htm. Accessed May 2010.
National Heart, Lung and Blood Institute. National Cholesterol Education Program Guidelines, Cholesterol, ATP III. Pp 31-34. PDF available for download at http://www.nhlbi.nih.gov/guidelines/cholesterol/atp3full.pdf through http://www.nhlbi.nih.gov. Accessed May 2010.
OhioHealthOnline. VLDL cholesterol: What is it? Available online at http://www.ohiohealth.com/bodymayo.cfm?xyzpdqabc=0&id=6&action=detail&ref=2755 through http://www.ohiohealth.com. Accessed May 2010.