The conventional method for measuring the levels of cholesterol and other lipids is by taking a venous blood sample. Most laboratories measure total cholesterol, HDL cholesterol, and triglycerides as part of their routine screening test. Since both cholesterol and triglycerides are carried in the blood by being wrapped up in proteins, it is the proteins which are actually measured. The total cholesterol (TC) consists of three major components -- LDL, HDL, and VLDL (the lipoprotein carrying triglyceride). Although LDL is the most important of the three for causing vascular disease, there is no convenient way for measuring it directly, so it has to be estimated from measurements of the others. The formula that is used is:

LDL chol = Total chol - HDL chol - Triglycerides/5

There are also automatic analyzers which will give an instantaneous reading of total cholesterol from a small sample of blood taken from a finger stick. They are less accurate than the conventional method, however, and we do not recommend them.