The main methods of monitoring jaundice are blood tests for bilirubin or transcutaneous jaundice tests for bilirubin. Regardless of the method used, the normal value of bilirubin is less than 17 umol/L. Generally, the bilirubin value from a blood test is more accurate. Bilirubin is a breakdown product of the metabolism of tetrapyrrole and hemoglobin. Most bilirubin comes from the degradation of hemoglobin, and in the serum, bilirubin is usually divided into direct and total bilirubin and indirect bilirubin. Of these three tests, jaundice occurs once bilirubin levels rise above a certain value. This is mainly due to excessive bilirubin production or the liver’s own ability to break down bilirubin, which enters the body’s bloodstream and circulates to the skin or sclera where jaundice occurs. Elevated bilirubin can occur not only in adults, but also in children, especially newborns. In adults or children, bilirubin levels are considered abnormal if they exceed the limit. However, newborns are unique in that there is a distinction between pathological jaundice and physiological jaundice. This means that a newborn does not have an elevated bilirubin level as an abnormal condition. Generally speaking, newborns always have jaundice after birth, and the bilirubin in their blood tests is definitely over the limit. However, as long as it subsides within 2 weeks and does not rebound, or does not exceed a certain value, it will be considered normal. Pathological jaundice in newborns is different, with persistent jaundice that does not subside and a persistent increase in bilirubin. The value of jaundice is mainly determined by testing the bilirubin level, and its normal value is clearly defined. However, it is not a sign of disease if it exceeds the normal value, and this is something that needs to be distinguished.