Serum total bile acid 21 μmol/L is not normal. The normal range of serum total bile acid is 0~10μmol/L. 21μmol/L is abnormal and belongs to the elevation of serum total bile acid, which may be caused by physiological reasons, liver diseases, biliary obstruction and other reasons. 1. Physiological reasons: it may be caused by dietary factors, which often leads to a transient increase in total bile acids, but will gradually return to normal. 2. Liver diseases: most common in hepatitis, drug-related liver injury, cirrhosis, etc., which will lead to a decrease in the liver’s ability to metabolize cholesterol, resulting in cholestasis and elevation of total bile acids in the serum. 3. Biliary tract obstruction: for example, gallstones, bile duct cancer, cholecystitis, etc., may lead to biliary tract obstruction, thus affecting the normal excretion of bile acids, which will result in elevated total bile acids. Elevated serum total bile acids may also be caused by other reasons, it is recommended to consult a doctor in time, under the guidance of the doctor for targeted treatment. Please do not take medication on your own to avoid delaying your condition.