Red cell distribution width (RDW) in the diagnosis of iron deficiency with microcytic hypochromic anemia.

Objective: To study the utility of red cell distribution width (RDW) in the diagnosis of iron deficiency among children with microcytic hypochromic anemia.

Methods: 151 children (6 months-12 years) with microcytic (MCV<75 fl) anemia were classified into iron deficient (IDA) and non-iron deficient anemia (non-IDA) on the basis of serum ferritin and total iron binding capacity (TIBC). RDW values were obtained on an automated hematology analyzer. Receiver operator curves (ROC) were constructed and the utility of RDW in diagnosis of iron deficiency was studied.

Results: The mean RDW value was 18.37+/-2.22% in IDA group (97 children) compared to 16.55+/-1.51 % in the non-IDA group (54 children) (p<0.0001, unpaired t test). In IDA group, the mean RDW value was 16.60+/-1.78%, 17.95+/-1.91% and 20.55+/-1.32% among mild, moderate and severely anemic children (p<0.0001, ANOVA test). The corresponding values in non-IDA group were 16.03+/-1.25%, 16.76+/-1.20% and 16.77+/-2.68% respectively (p=0.269, ANOVA test). At a cut-off value of 17.4%, as obtained from the ROC curve, the sensitivity and specificity of RDW in diagnosis of IDA were 81.0% and 53.4% and a positive and negative predictive value of 63.0% and 72.2% respectively.

Conclusion: RDW has a limited specificity for diagnosis of IDA among children with microcytic hypochromic anemia.