Differentiation between Anemia of Chronic Disease and Iron Deficiency Anemia Using Newer Erythrocyte Parameters

Abstract

Both Iron deficiency anemia (IDA) and anemia of chronic disease (ACD) can present as microcytic anemia. It is important to differentiate between the two, because the treatment is different. In patients presenting with microcytic anemia, bone marrow is often required for differentiation between IDA and ACD. But since bone marrow is an invasive and cumbersome procedure, newer erythrocytic parameters and reticulocyte indices are being studied in differentiation of these two entities. Life span of Reticulocyte is just 1-2 days compared to 120 days of that of an RBC. Therefore, the decrease in reticulocyte hemoglobin content occurs much earlier than an erythrocyte. This makes reticulocyte indices early and reliable indicators of IDA. We explored the value of reticulocyte hemoglobin (Ret Hb) and percentage microcytic RBCs (%Micro R) in the differentiation of both these conditions with bone marrow iron studies being the gold standard.

Material: Overall 130 patients with iron deficiency anemia and anemia of chronic disease were recruited and they underwent detailed evaluation including RBC indices, Ret Hb, %Micro R, serum iron studies, bone marrow examination including estimation of bone marrow iron. The diagnostic accuracy of Ret Hb and %Micro in differentiation between the two conditions was determined.

Observation: Ret Hb was found to be positively correlated to serum iron, ferritin and TIBC in diagnosing IDA. At a cut-off value of RET HB of 27 pg/mL, the diagnosis of IDA could be made at a sensitivity of 93.4% and a specificity of 95.83%. Positive predicitive value for Ret Hb was 99% and negative predicitive value was 76.6%. RET HB was found to have best diagnostic efficiency (area under the curve 0.96) on ROC analysis in the differentiation of these two conditions. MICRO R was found to be inferior to other parameters (AUC of 0.39) in the differentiation of these two conditions.

Conclusion: Ret Hb differentiates iron deficiency anemia from anemia of chronic disease with a high accuracy rate of 96%. It can be used as a marker of IDA across all situations.