Low total bilirubin is mostly seen in anemia, nephritis and cancer caused by various reasons. First of all, bilirubin is the product of metabolic decomposition of hemoglobin in the liver, so low total bilirubin is mostly due to insufficient production of raw materials, i.e., hemoglobin, and this is also often referred to as anemia, which is caused by a variety of reasons, usually iron deficiency anemia, megaloblastic anemia, and hemolytic anemia and so on. In addition, zinc deficiency can also cause a decrease in total bilirubin, which is often seen in anorexic people. Therefore, if the indicators do not produce deviations, it is recommended to further check the blood count, red blood cell morphology, serum ferritin and other indicators. In addition, diseases such as nephritis and cancer should be excluded, as they can also cause anemia secondary to the disease.