Common causes of low HDL include genetic factors, poor lifestyle, chronic liver disease and so on. The normal reference range of HDL is 1.16-2.42mmol/L. HDL has anti-atherosclerotic effect, which can reduce the risk of coronary heart disease and other diseases, therefore, it is necessary to analyze the specific causes of low HDL. 1. Genetic factors: HDL level is obviously affected by heredity, if it is low due to genetic factors, it is generally not accompanied by disease states, and at the same time, HDL level is stable and does not change with the improvement of disease and nutritional status, so there is no need for special intervention. 2. Adverse lifestyle: high-fat diet, irregular work and rest, smoking, etc. may lead to a decrease in HDL. Since HDL is beneficial to the body, it is necessary to actively improve bad habits and improve the index. 3. Chronic liver disease: Hepatitis and cirrhosis can lead to low HDL, which requires the use of drugs such as polyene phosphatidylcholine to protect the liver and actively treat the primary disease. Low HDL is generally considered to be of no benefit to the body, and it is recommended to consult a doctor as soon as possible to clarify the cause and intervene.