A 50-year-old woman complains of pain and swelling in her proximal interphalangeal joints, both wrists, and both knees. She complains of morning stiffness. She had a hysterectomy 10 years ago. Physical examination shows swelling and thickening of the PIP joints. Hemoglobin is 10.3 g/dL, MCV is 80 fL, serum iron is 28 µg/dL, iron-binding capacity is 200 µg/dL (normal 250-370 µg/dL), and saturation is 14%.
Which of the following is the most likely explanation for this woman’s anemia?A. Occult blood loss
Patients with chronic inflammatory or neoplastic disease often develop anemia of chronic disease. Cytokines produced by inflammation cause a block in the normal recirculation of iron from reticuloendothelial cells (which pick up the iron from senescent red blood cells) to the red cell precursors (normoblasts). The peptide hepcidin is felt to be the main mediator of the effect. This defect in iron reutilization causes a drop in the serum iron concentration and a normocytic or mildly microcytic anemia. The inflammatory reaction, however, also decreases the iron-binding capacity (as opposed to iron-deficiency anemia, where the iron-binding capacity is elevated), so the saturation is usually between 10% and 20%. The anemia is rarely severe (Hb rarely < 8.5 g/dL). The hemoglobin and hematocrit will improve if the underlying process is treated. Diseases not associated with inflammation or neoplasia (ie, congestive heart failure, diabetes, hypertension, etc) do not cause anemia of chronic disease. Blood loss causes a lower serum iron level, an elevated iron-binding capacity, and a lower iron saturation. The serum ferritin (low in iron deficiency, normal or high in anemia of chronic disease) will usually clarify this situation. Vitamin B12 and folate deficiencies are associated with macrocytic anemia. Sideroblastic anemia can be either microcytic or macrocytic (occasionally with a dimorphic population of cells, some small and some large), but is associated with an elevated iron level. In addition, this patient’s history (which suggests an inflammatory polyarthritis) would not be consistent with sideroblastic anemia. The diagnosis of sideroblastic anemia is made by demonstrating ringed sideroblasts on bone marrow aspirate. In the anemia of chronic renal insufficiency, the iron studies are normal and the red cells are normocytic.