Jaundice is a common symptom and sign. It occurs due to the increase in serum bilirubin concentration caused by bilirubin metabolism disorder. Clinically, the sclera, mucous membranes, skin and other tissues are stained yellow. Because the sclera contains more elastin, which has a strong affinity with bilirubin, the yellow staining of the sclera of jaundice patients is often first noticed before the mucous membranes and skin. When the total serum bilirubin is between 17.1 and 34.2 μmol/L, and jaundice is not visible to the naked eye, it is called latent jaundice or subclinical jaundice; when the total bilirubin concentration in the blood exceeds 34.2 μmol/L, jaundice can be found clinically, which is also called overt jaundice.