Very Low Density Lipoprotein (VLDL)
At a Glance
Why Get Tested?
As part of vascular risk assessment
When to Get Tested?
When other tests are being done to assess vascular risk
Sample Required?
A blood sample taken from a vein in your arm
The Test Sample
What is being tested?
Very low density lipoprotein is one of the three major lipoprotein particles. The other two are high density lipoprotein (HDL) and low density lipoprotein (LDL). Each particle contains a mixture of cholesterol, triglyceride and protein, but in varying amounts unique to each type of particle. VLDL contains the highest amount of triglyceride and is called a triglyceride rich lipoprotein. 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.
At present there is no simple direct way of measuring cholesterol in VLDL and so it is estimated from triglyceride which is mainly present in VLDL. The calculation used is not valid when the triglyceride level is greater than 4.5 mmol/L.
The VLDL cholesterol concentration can be measured directly using a technique called ultracentrifugation. However, this technique is not straightforward and not usually done in clinical laboratories. This test is generally carried out in specialist laboratories, most often for research purposes.
How is the sample collected for testing?
The test for VLDL uses a blood sample collected by venipuncture using a needle to collect blood from a vein in the arm.
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.
The Test
How is it used?
VLDL may be reported with results from a lipid profile, a group of tests that are often requested together to help work out the risk of coronary heart disease but it is not reported by most laboratories. Since VLDL contains most of the circulating triglyceride and since the composition of the different particles is relatively constant, it is possible to estimate the amount of VLDL cholesterol by dividing the triglyceride value (in mmol/L) by 2.2. A high level is associated with increased risk of heart disease and stroke.
Measurement of the VLDL cholesterol levels are also used to help in the diagnosis of a rare disease called familial dysbetalipoproteinaemia (also known as a type III hyperlipidaemia). This hyperlipidaemia is usually has elevated levels of cholesterol and triglyceride in the blood and sometimes yellowish coloured streaks on the palms of the hands called palmar xanthomata. IDL levels can be increased in familial dyslipoprotein but since IDL is not normally present in blood it may be interpreted as VLDL.
When is it requested?
It may be requested as part of an assessment for the risk cardiovascular disease or if a diagnosis of familial dysbetalipoproteinaemia is suspected.
What does the test result mean?
An elevated level is a risk factor for heart disease and may indicate the need for lifestyle change and drug treatment aimed at lowering lipid levels and so reducing the risk. In familial dysbetalipoproteinaemia the ratio of VLDL cholesterol to total triglyceride exceeds 0.3.
Is there anything else I should know?
Common Questions
Ask a Laboratory Scientist
Article Sources
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.
