LDL 3.9mmol/L is at the borderline elevated level, which can be lowered with the help of lifestyle intervention. If the intervention is ineffective or the patient is accompanied by other diseases or risk factors, medication can be given in accordance with the doctor’s prescription. According to the Chinese standard for the prevention of atherosclerotic cardiovascular disease, the ideal level of LDL cholesterol is <2.6 mmol/L; the appropriate level is <3.4 mmol/L; the borderline elevated level is ≥3.4 mmol/L but <4.1 mmo/L; and the elevated level is ≥4.1 mmo/L. Therefore, the LDL cholesterol level is <4.1 mmol/L, which is the ideal level for atherosclerotic cardiovascular disease. Thus an LDL cholesterol of 3.9 mmol/L is a borderline elevated level. In healthy individuals with borderline elevated LDL, lifestyle interventions can be used to lower LDL levels. For example, they can be physically active, adjust their diet to a light, low-salt, low-fat diet, and increase the intake of vegetables. If you are obese or overweight, you should actively lose weight. However, for high LDL caused by hereditary hyperlipoproteinemia, hypothyroidism, nephrotic syndrome, cholestatic jaundice, or if the patient has other risk factors such as coronary heart disease, hypertension, diabetes mellitus and so on, it is necessary to give medications to regulate blood lipids, such as Simvastatin Tablets, Atorvastatin Calcium Tablets and other medications. Before using the medication, you need to go through the doctor's scientific assessment and follow the doctor's prescription to avoid unnecessary harm to the body caused by random use of medication.