Total serum cholesterol is the sum of cholesterol contained in all lipoproteins in the blood, including free cholesterol and cholesteryl esters. The ideal total cholesterol level for a normal adult is 2.83 mmol/L-5.20 mmol/L. If a patient’s total cholesterol level is at 5.9 mmol/L, the patient’s physical condition needs to be evaluated to rule out any risk factors. If the patient has no atherosclerotic disease and no risk factors for coronary heart disease, then the total cholesterol level of 5.9mmol/L is at the critical value and although it is mildly elevated, no special treatment is needed. Pay attention to improving daily living habits, such as exercising more, avoiding sedentary lifestyle, etc., improving poor dietary habits, eating less fatty foods and foods with high cholesterol content, such as fried chicken and squid, and eating more fresh vegetables and fruits. The total cholesterol level can be restored to normal. Patients with poor body image should actively lose weight and control their weight. If patients have atherosclerosis in combination or have other risk factors, they should go to the hospital in time and take medications strictly according to medical advice to lower the total serum cholesterol level so as not to induce hypercholesterolemia, which may lead to further diseases such as gallbladder polyps, gallbladder stones and common bile duct stones. In addition, low total serum cholesterol can induce anemia, hyperthyroidism and other diseases, and patients should be closely monitored and treated in a timely manner.