USMLE – Anemia of Chronic Disease
This is a common type of anemia, particularly in hospital populations. Characteristic features are as follows:
-The anemia occurs in the setting of chronic infections, chronic inflammation, or neoplasia,
-The anemia is not related to bleeding, hemolysis or marrow infiltration.
-The anemia is generally mild, in the range 85-115 g/l and is usually associated with a normal MCV (normocytic normochromic), but up to 25% may have a reduced MCV.
-The serum iron is low but iron stores are normal or increased, as indicated by the ferritin or stainable marrow iron.
The pathogenesis of this type of anemia is thought to involve abnormalities of iron metabolism and erythropoiesis. Recent interest has been centered on the role of erythropoietin and the inhibitory effect of various cytokines (interleukin-l and tumor necrosis factor alpha) on erythropoiesis. Erythropoietin levels appear to be lower than would be expected for the degree of anemia. Administration of erythropoietin to patients with rheumatoid arthritis has a beneficial effect on the anemia.
A panicular problem is to distinguish the anemia of chronic disease (ACD) associated with a low MCV from iron deficiency. The ferritin level is elevated in inflammatory conditions and the serum iron is low in both the ACD and iron deficiency. A ferritin in the low/normal range (up to 100 ug/l) in the setting of disorders associated with the ACD may indicate iron deficiency. Examination of the marrow is useful to assess iron stores. A trial of oral iron could be given in difficult situations. A positive response occurs in true iron deficiency but not in ACD. Measures which reduce the severity of the underlying disorder generally help to improve the ACD.