Lipoprotein Subfraction Testing

Although there is a genetic component, lipoprotein subfractions can be altered by adopting a diet low in saturated fats, losing excess weight, and exercising regularly. The use of lipid-lowering drugs may also affect the subfraction distribution.

Very Low Density Lipoprotein (VLDL) is one of three major lipoprotein particles. The other two are high density lipoprotein (HDL) and low density lipoprotein (LDL). Each one of these particles contains a mixture of cholesterol, protein, and triglyceride, 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 contains the highest amount of triglyceride. Since VLDL contains most of the circulating triglyceride and since the compositions of the different particles are relatively constant, it is possible to estimate the amount of VLDL-cholesterol by dividing the triglyceride value (in mg/dL) by 5. At present, there is no simple, direct way of measuring VLDL-cholesterol, so the estimate calculated from triglyceride is used in most settings. This calculation is not valid when the triglyceride is greater than 400 mg/dl. Increased levels of VLDL-cholesterol have been found to be associated with increased risk of heart disease and stroke.