A blood draw for jaundice should look at the serum bilirubin concentration. Normal serum total bilirubin concentration is 1.7 to 17.1 μmol/L. When the total bilirubin value is too high, the patient may show symptoms of jaundice. Jaundice is the clinical manifestation of hyperbilirubinemia. The main indicator of hyperbilirubinemia is that the bilirubin in the blood is elevated. Measurement of serum total bilirubin is an important test in liver and biliary function tests. It can accurately reflect the degree of jaundice and is important for clinical diagnosis of hidden jaundice. The normal value of serum total bilirubin is 1.7-17.1 μmol/L. When the serum total bilirubin concentration is low, it can be measured as a percentage of the total bilirubin concentration. When the serum total bilirubin concentration is between 17.1 and 34.2 μmol/L, jaundice is not visible to the naked eye. When the serum total bilirubin concentration exceeds 34.2μmol/L, obvious symptoms of jaundice can appear, such as yellowing of the skin, yellowing of the whites of the eyes, urine as dark as strong tea, and feces that look like clay color. When the serum total bilirubin is elevated, one should consult the doctor in time and follow the doctor’s instructions for active treatment.