Cholesterol and other fats (lipids) have to be transported in the blood attached to a protein. These combinations are called lipoproteins. Lipoproteins are categorized by the ratio of lipid content to protein content. Protein is more dense than lipid. High-density lipoprotein (HDL) contains more protein than lipid. Low-density lipoprotein (LDL) contains more lipid than protein. The risk for atherosclerosis depends on both the type and degree of cholesterol elevation. LDL elevation increases the risk for atherosclerosis in proportion to its elevation beyond normal limits. Conversely, HDL elevation decreases the risk for atherosclerosis. For this reason, HDL is sometimes referred to as "good cholesterol" and LDL as "bad cholesterol". The ratio of total cholesterol and HDL is another factor used to assess the risk for atherosclerosis based on lipid profiles. Ratios of 4 or less are more favorable.
Abnormal lipid studies and other possible risk factors for atherosclerosis should be discussed with your personal physician. For additional and more complete information on Tests for Blood Lipids, the following web sites are recommended: