Whether creatinine 99μmol/L at 40 years old is normal or not depends on the situation, if it is male, it is within the normal range, and it is necessary to check the renal function regularly to avoid renal damage. If you are a woman, the creatinine is generally high, you need to clarify the cause of creatinine elevation is physiological or pathological, treat the cause and regular review, and pay attention to avoid aggravating renal damage. Creatinine is an important indicator for evaluating kidney function, generally speaking, the normal value of blood creatinine is 53-106 μmol/L for men and 44-97 μmol/L for women, which is normal for men, and regular review of renal function is needed to avoid kidney damage. In women, it is generally high. Elevated creatinine can be seen in physiological conditions, such as strenuous exercise, overconsumption of meat, etc., generally do not need to be treated, regular review can be; for pathological conditions, such as diarrhea, gastrointestinal bleeding, drug damage, glomerulonephritis, etc., it is necessary to remove the causative factors based on the causes of the relevant causes of targeted treatment, such as rehydration, control of blood pressure, blood glucose, immunosuppression and other therapies. Life should pay attention to avoid overwork and infection. When abnormal creatinine results are found, it is recommended to go to a regular hospital in time to consult a doctor, and follow the doctor’s instructions to standardize the treatment after clarifying the cause of the disease.