Serum erythropoietin and circulating transferrin receptor in thalassemia intermedia patients with heterogeneous genotypes

Background. Thalassemia intermedia patients usually do not require blood transfusions; however, all show variable degrees of erythropoietic marrow expansion to compensate for more or less marked anemia, and this represents the major cause of complications in untransfused individuals. Materials and Methods. To assess the degree of erythropoietic expansion in thalassemia intermedia, serum erythropoietin (sEpo) and serum transferrin receptor (sTfr) were determined in thirty Italian patients characterized by their β-globin genotype. Results. Six patients showed inappropriately low sEpo levels (O/P ratio <0.85). Even excluding these cases, no clear relationship was observed between Hb levels and sEpo or sTfr. Two groups of patients were compared: the first with low HbF (+ genotypes, and the second with high HbF (>40%) that contained a prevalence of β(o) genotypes. Hb levels were similar in the two groups: 8.09±1.15 g/dL in low HbF and 8.82±1.28 g/dL in high HbF patients. Mean sEpo was 112±78.02 mU/mL (O/P ratio = 0.98±0.22) in the first and 246.62±184.30 mU/mL (O/P ratio = 1.25±0.30) in the second group, with a statistically significant difference, as expected, because of HbF oxygen hyperaffinity. No significant difference in sTfr levels was observed, indicating a comparable erythropoietic response in the two groups. Conclusions. The relationships between anemia, HbF and total erythropoiesis in thalassemia are more complex than expected. Further studies of subjects with high HbF and benign conditions, such as HPFH, could be of help in clarifying this point, to the aim of safely increasing HbF in thalassemia intermedia.