The timing of hemoglobin supplementation needs to be based on the degree of its deficiency and cannot be generalized. According to the degree of hemoglobin reduction, there are four levels. Mild patients with hemoglobin >90g/L need as soon as 1 month to recover; moderate patients with hemoglobin between 90-60g/L need as soon as 2 months to recover; severe patients with hemoglobin 60-30g/L need as soon as 3 months to recover; extreme patients with hemoglobin <30g/L need as soon as 4 months to recover. Generally speaking, low hemoglobin is a manifestation of anemia. usually, hemoglobin can be gradually restored to 110g/L after supplementing with iron and increasing protein nutrition, usually after 2-3 months of conditioning. while supplementing iron, patients also need to supplement folic acid and vitamin B12 to promote iron absorption, which helps to improve hemoglobin level. In addition, patients can also take appropriate supplements of foods rich in iron, protein and vitamin B12, such as beef, red dates, egg yolks, dark green vegetables and fruits, which are also useful in raising hemoglobin levels.