A simplified diagnostic pathway for the differential diagnosis of iron deficiency anaemia and anaemia of chronic disease.

INTRODUCTION: Iron deficiency anaemia (IDA) and anaemia of chronic disease (ACD) are common causes of anaemia with similar clinical and laboratory features. IDA is caused by low iron stores while ACD is due to iron-restricted erythropoiesis occurring in inflammatory states. Differential diagnosis requires analysis of multiple biochemical and haematological parameters. IDA can occur simultaneously to ACD (mixed aetiology). It is essential that true iron deficiency is identified, as these patients will require iron therapy. This preliminary study investigated whether hepcidin, the master regulator of iron homeostasis, in conjunction with reticulocyte haemoglobin equivalent (RetHe) has the potential to differentiate IDA from ACD, and to exclude IDA in patients with mixed aetiology. METHODS: Hepcidin concentration (measured using a commercially available ELISA method), RetHe, and iron parameters along with C-reactive protein (CRP) were analysed in 77 Gastroenterology patients with anaemia in a secondary care setting. RESULTS: Receiver operator characteristic (ROC) analysis showed that hepcidin at an optimal cut-off concentration of <6ng/ml could identify IDA with a sensitivity and specificity of 88.9% and 90.6% respectively and could distinguish ACD from IDA with both a sensitivity and specificity of 100% at a cut-off of >46ng/ml. Identifying true IDA in mixed aetiology patients could be achieved by RetHe analysis and applying an optimal cut-off of <30pg. CONCLUSION: Hepcidin, in conjunction with RetHe, offers a new simplified diagnostic pathway for differential diagnosis of IDA and ACD, thereby reducing the diagnostic turnaround time and allowing appropriate treatment of patients with a true iron deficiency.