Altered, most often excessive, concentration of lipids in blood - Result of a genetic predisposition, secondary causes, or of a combination of both- Three forms: o Hypercholesterolemia o Hypertriglyceridemia o Mixed forms - Cholesterol-carrying lipoproteins are differentiated on the basis of their buoyant properties as LDL, VLDL, and HDL and may vary on the amount of cholesterol present in each particle, in the number of circulating particles, or both - Hypercholesterolemia and hypertriglyceridemia per se do not produce specific symptoms, unless associated with the disease of an organ involved in the metabolism of lipid (e.g., pancreatitis) - Some clinical manifestations of atherosclerosis occur after decades of silent onset and progression of lesions - Acute hypercholesterolemia is not known to occur as adverse response to drug - Acute hypertriglyceridaemia may be the expression of excessive (binge-like) consumption of fat-rich foods or alcohol, or it may relate to diabetes - especially when not properly controlled - or pancreatitis.