Red blood cell distribution width in the anemia secondary to tuberculosis.

A study was done to explore the claim that anisocytosis as measured by the red blood cell volume distribution width (RDW) is raised in iron-deficiency anemia, but is normal in the anemia of chronic disorders. Measurements were done on 283 normal patients, 22 iron-deficient patients, and 102 tuberculotic patients, using a model S plus Coulter Electronic Counter with standard calibration. Mean (+/- SD) values for RDW were as follows: normals, 7.36 (+/- 0.57); untreated iron deficiency, 10.39 (+/- 1.37); and 15 untreated anemic patients with tuberculosis, 10.44 (+/- 0.63). Mean values remained above 10.4 in 69 patients with tuberculosis during treatment, irrespective of whether or not the patients were anemic, but had fallen towards the normal mean (8.49 +/- 0.8) in the 18 subjects in whom it was measured at the end of therapy. By this time the mean corpuscular volume (MCV) and hemoglobin concentrations had risen to normal. It is concluded that RDW values in the chronic inflammatory disorder tuberculosis are not significantly different from those occurring in iron-deficiency anemia.