Normal values for blood monoamine oxidase (MAO) range from 8 to 31 U/ml. Blood list amine oxidase (MAO) exists in mitochondria and catalyzes the oxidative deamination of monoamines, which are oxidative enzymes of biogenic amines produced by the body itself. MAO is an indicator of liver fibrosis and cirrhosis. In people with liver fibrosis or cirrhosis, serum albumin and total bilirubin values tend to decrease, accompanied by an increase in monoamine oxidase values. Due to the different test methods and standardized values, the reference range of MAO may be different in different hospitals, so you can refer to the test report form for details. When MAO is abnormally elevated, it is recommended that further examination be conducted for timely treatment.