Patients with acute nephritis often do not experience anemia. If a patient with acute nephritis develops anemia, further examination is necessary to determine whether rapidly progressive glomerulonephritis is present. The mechanisms of anemia include hemorrhagic anemia, anemia due to the destruction and dissolution of red blood cells, and anemia due to decreased bone marrow hematopoietic capacity. Hemorrhagic anemia is commonly seen in cases of excessive menstrual flow or chronic blood in stools, which can occur in conditions such as liver cirrhosis, gastric ulcer, enteritis, and intestinal cancer. Anemia resulting from the breakdown of red blood cells often occurs in cases of splenomegaly or when the body produces antibodies against red blood cells, leading to autoimmune hemolysis. A decrease in bone marrow hematopoietic capacity is typically seen in related diseases such as leukemia, myeloma, or renal anemia, or when the patient's dietary intake of nutrients is insufficient, leading to reduced bone marrow hematopoietic capacity. Overall, for acute nephritis, if anemia occurs, it is important to identify the cause, which may not be closely related to acute nephritis itself.