HDL is one of the blood lipids. There are four general indicators of blood lipids: cholesterol, triglycerides, LDL, and HDL. For example, hypercholesterolemia means elevated serum cholesterol; in the case of hypertriglyceridemia, elevated serum triglycerides; in the case of mixed hyperlipidemia, elevated serum total cholesterol and triglycerides; in the case of reduced HDL, it means low HDL, which is also a type of dyslipidemia. In short, if hypercholesterolemia or hypertriglyceridemia, or mixed hyperlipidemia or low HDL is found, in either case, treatment is necessary to prevent atherosclerosis, plaque and narrowing of blood vessels, which can lead to cerebral and cardiac infarction and a series of dangerous events. HDL is a type of blood lipid, and if it is low, it is low HDLemia, which can also cause atherosclerosis. In short, if there is dyslipidemia, we say that we should actively treat it.