As part of vascular risk assessment
Very Low Density Lipoprotein (VLDL)
When other tests are being done to assess vascular risk
A blood sample taken from a vein in your arm
Usually fasting for 9-12 hours before the test (only water permitted) and no alcohol for 24 hours before the test; follow any instructions you are given.
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.
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.