Low prealbumin up to <100 mg/L can be considered malnutrition or severe liver impairment. The normal value of prealbumin in adults is 280~360mg/L, and the reference range may vary with different testing methods. Prealbumin is synthesized by liver cells and has a shorter half-life than other albumin, so it can reflect liver cell damage earlier than albumin. The level of prealbumin is affected by the nutritional status of the body and the state of liver function. Prealbumin and albumin depletion is mostly due to the patient's generalized hypermetabolic state or poor nutritional state, normal liver synthesis is difficult to meet the body's metabolic needs. Lower prealbumin may be considered clinically in patients with high consumption (severe malnutrition, chronic severe infections and advanced malignant tumors) and low production (acute severe hepatitis, cirrhosis and other liver diseases).