The formula for calculating residual cholesterol is: residual cholesterol (RC) = total cholesterol (TC) – high-density lipoprotein cholesterol (HDL-C) – low-density lipoprotein cholesterol (LDL-C). Total cholesterol is categorized into HDL, LDL, IDL, very LDL, celiac particle residue, and celiac microparticles. LDL particles can enter the inner lining of the arteries, which can lead to the development of atherosclerosis. Intermediate density lipoprotein (IDL), very low density lipoprotein (VLDL) and celiac residue particles also enter the arterial lining and are collectively known as residual cholesterol. According to the European Atherosclerosis Society guidelines, high residual cholesterol is defined as fasting residual cholesterol ≧0.8mmol/L and/or postprandial residual cholesterol ≧0.9mmol/L. Studies suggest that residual cholesterol can be used to assess cardiovascular risk, and that elevated levels of residual cholesterol are associated with a significant increase in the risk of cardiovascular events. Abnormal lipid test results are recommended to seek medical advice for lifestyle or pharmacological interventions.