Erythrocyte labile iron pool indicating concealed iron overload in non-transfusion-dependent β-thalassemia

Abstract

Objectives: Not only do transfusion-dependent thalassemia (TDT) patients have a risk of clinical consequences arising from iron overload, non-transfusion-dependent thalassemia (NTDT) patients may encounter it also. In this study, we demonstrated the usefulness of intra-erythrocyte labile iron pool (LIP) measurement in NTDT patients with HbE/β-thalassemia in revealing a concealed iron overload and the resultant oxidative cell damage. Methods: LIP and ferritin levels were assayed in 20 HbE/β-thalassemia patients, comprising 10 NTDT and 10 TDT patients and 10 healthy individuals. Erythrocyte oxidative stress parameters (intraerythrocyte reactive oxygen species (ROS) levels, numbers of erythrocyte vesicles, and cell apoptosis) were also determined and their correlations to LIP and ferritin levels were analyzed. Results: LIP levels (based on different mean fluorescence intensity (MFI) values obtained by flow cytometry) were high in both the NTDT (54 [42–90]) and TDT (71 [68–77]) patients compared to the healthy individuals (43 [31–61]). The ferritin level observed in the NTDT group (2,149 [781–4,071] ng/mL) was lower than that of the TDT group (4,885 [2,343–7,826] ng/mL). The LIP level was significantly correlated with the NTDT patients’ age and all oxidative stress parameters, but the ferritin level was not. Correlation analysis predicted that NTDT patients without receiving any therapy aged 32.5 years old or over are likely at risk of iron overload status and oxidative cell damage. Conclusions: The results indicate that LIP may be a helpful alternative parameter for defining the risk of iron overload.