The normal range of total cholesterol in adults is 2.83~5.20mmol/L. If the total cholesterol is 6.8mmol/L, it is considered hypercholesterolemia. Cholesterol is a major component in the synthesis of bile acids, sex hormones, adrenocorticotropic hormone, vitamin D and other active substances, as well as in the composition of cell membranes, and its concentration in the serum of the body can be used as an indicator of lipid metabolism. Total cholesterol is the sum of cholesterol contained in all lipoproteins in the blood. Elevated levels of total cholesterol can be caused by genetic factors, lifestyle and diseases. 1. Genetic factors: Mutations in the genes of enzymes or receptors related to lipoprotein metabolism in the human body can cause a significant increase in total cholesterol levels. 2. Lifestyle: Long-term consumption of high-cholesterol, high-fat and high-calorie foods can lead to elevated total cholesterol levels. 3. Disease: Pathological elevation is usually seen in atherosclerosis, diabetes, hypothyroidism, nephrotic syndrome and other diseases. If total cholesterol is elevated, it is necessary to consult a doctor in time to find out the cause and standardize the treatment under the doctor’s guidance.