| disease | Chronic Infection, Inflammation, and Renal Anemia |
| alias | Anemia |
Chronic infections, inflammation, and renal anemia (anemia of chronic infection, inflammation, and renal disease) are anemias secondary to systemic diseases. They are commonly seen in chronic suppurative infections such as osteomyelitis, lung abscess, empyema, and bronchiectasis; connective tissue diseases like wind-dampness heat, rheumatoid arthritis, lupus erythematosus, and ulcerative colitis. Additionally, chronic progressive kidney diseases, immunodeficiency disorders, and others often present with anemia.
bubble_chart Pathogenesis
It varies depending on the primary diseases, but the following conditions are often the main causes:
1. Shortened red blood cell lifespan: During chronic infections, the mononuclear-macrophage system proliferates and becomes hyperactive, leading to premature destruction of the patient's own red blood cells, reducing their lifespan from 120 days to around 80 days. Transfused red blood cells are similarly destroyed.
2. Weakened bone marrow compensatory capacity: Normally, the bone marrow has a strong compensatory ability. If the red blood cell lifespan is mildly to moderately (grade II) shortened, compensation is easily achieved without resulting in anemia. However, during chronic infections, despite increased erythropoietin production due to anemia-induced hypoxia, the bone marrow responds poorly and fails to increase red blood cell production.
3. Impaired iron utilization: In both acute and chronic infections, serum iron levels significantly decrease, and total iron-binding capacity also declines, while iron storage increases. Bone marrow examination reveals elevated iron content within cells, but the release of iron from the reticuloendothelial system into the plasma is reduced—a phenomenon known as mononuclear-macrophage system blockade. Additionally, while iron absorption typically increases in general anemia, it decreases during infections. These iron metabolism abnormalities can be corrected after the infection resolves.
Other factors include the use of salicylic acid to treat wind-warmth arthritis, which often causes minor chronic intestinal blood loss. Chronic renal failure leading to reduced erythropoietin production can also result in anemia.bubble_chart Clinical Manifestations
The severity of anemia depends on the underlying disease. In acute infections, anemia is usually mild, presenting only with general symptoms such as pale complexion, lack of strength, and rapid heart rate. However, when secondary to renal anemia, the symptoms are often more severe.
bubble_chart Auxiliary Examination
Anemia is grade I or grade II, with hemoglobin mostly ranging from 60 to 90 g/L (6 to 9 g/dL), and a corresponding decrease in red blood cells. It is a normocytic normochromic anemia. Severe anemia may present as microcytic hypochromic anemia. Reticulocyte counts are normal or decreased. Platelet counts are normal, while white blood cells are often elevated. Free erythrocyte protoporphyrin is not elevated or shows grade I elevation (>35 μg/dL). Serum iron is decreased, averaging around 30 μg/dL, but total iron-binding capacity is not elevated, while serum ferritin is elevated. These two characteristics distinguish it from iron deficiency anemia. Bone marrow hyperplasia is adequate, with a normal granulocyte-to-erythrocyte ratio, and no compensatory hyperplasia of the erythroid system is observed. Bone marrow hemosiderin is increased.
bubble_chart Treatment Measures
The primary focus is on treating the underlying disease. If the infection can be controlled, the anemia will naturally lessen or disappear. Iron supplements, folic acid, and vitamin B12 are ineffective in treatment. Generally, blood transfusion is not required. For grade III renal anemia, concentrated red blood cells may be transfused.
