Red cap tubes are used for liver function blood draws. 1. The inner wall of the red cap tube is uniformly coated with silicone oil, which can prevent blood cells from attaching to the wall. Blood sampling needs to be done on an empty stomach, usually through a vein, after the blood naturally coagulates and the serum naturally precipitates out, the upper layer of plasma is taken for examination. Red cap tube can not only check liver function, but also used for thyroid function, serum immunology, tumor markers, electrolytes and other tests. 2. Liver function tests include total bilirubin, direct bilirubin, indirect bilirubin, total serum protein, albumin, albumin-globulin ratio, alkaline phosphatase, alanine aminotransferase, glutamic oxaloacetic aminotransferase, glutamyltransferase, and many others. Patients should be seen and examined at a local regular general hospital. In normal times, they should form good living habits and pay attention to reasonable dietary arrangements.