Differentiation of iron deficiency from thalassaemia trait: a new approach

Ricerca, B.M.; Storti, S.; d'Onofrio, G.; Mancini, S.; Vittori, M.; Campisi, S.; Mango, G.; Bizzi, B.

Haematologica 72(5): 409-413


ISSN/ISBN: 0390-6078
PMID: 3121463
Document Number: 3986
Red cell distribution width (RDW) is an index which represents red blood cell size variation. Using a Technicon H6000 instrument (Technicon Instruments Corp. NY 10059) we examined 298 patients who presented microcytosis (MCV<79 fl) and hypochromia (MCH<27 pg): 154 with thalassaemia trait, 124 with iron deficiency, 20 with both conditions. For each patient the RDW, three original ratios (RDW/RBC, RDWURBC2, RDWxMCV/RBC), and Mentzer's and Srivastava's formulae were evaluated. The mean values obtained for each parameter were significantly higher in the iron deficiency group than in the thalassaemia trait group (p<0.001). Furthermore, for each parameter a discriminant value was established. The thalassaemia trait patients were considered correctly classified if they showed values under the discriminant, and the iron deficiency patients if they showed values above it. Among the thalassaemic subjects 83.8% were correctly classified by RDW, 98.1% by RDW/RBC, 97.4% by RDWYRBC 2, 93.5% by RDWxMCV/RBC, 91.6% by Mentzer's formula and 91.6% by Srivastava's formula. In the iron deficiency group 66.9% of cases were correctly classified by RDW, 90.3% by RDW/RBC, 90.3% by RDW2/RBC2, 82.3% by RDWxMCV/RBC, 60.5% by Mentzer's formula, 63.7% by Srivastava's formula. Comparing the three ratios to Mentzer's and Srivastava's formulae, in thalassaemia trait patients RDW/RBC and RDW 2/RBC2 had a higher discriminating power than both formulae (p<0.05), while in iron deficiency all three ratios correctly classified a greater number of patients than the two formulae (p<0.001). Therefore we recommend the simplest of our ratios (RDW/RBC) as a new preliminary approach to distinguishing microcytic and hypochromic anemias.

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Differentiation of iron deficiency from thalassaemia trait: a new approach