“…3 Finally, recent investigations have revealed that a significant proportion of patients initially suspected of CDA I or II, based on both hypo-productive anemia and bone marrow morphological characteristics (Figure 2), were ultimately diagnosed with chronic anemia due to enzymatic defects, mainly pyruvate kinase deficiency (PKD) due to PKLR mutations. 12,34 To note, the presence of inadequate reticulocytosis, erythroblasts in peripheral blood, or immature forms at bone marrow examination, are frequently observed in patients with severe PKD. 35 Furthermore, evaluation of the main regulators of iron balance and erythropoiesis, that is, EPO, erythroferrone (ERFE), and hepcidin, showed comparable levels between CDA and PKD patients, 36 thus explaining the misdiagnosis between these conditions.…”