Serum erythropoietin and its determinants and associations in patients with haemoglobin E β-thalassaemia

Erythropoietin is a hormone that stimulates erythropoiesis. The role of erythropoietin in the pathophysiology of HbE β-thalassaemia, a subtype of thalassaemia, is understudied. Here, we aim to evaluate the determinants and associations of erythropoietin in HbE β-thalassaemia patients. We conducted a cross-sectional study in Thalassaemia Centres of Colombo North Teaching Hospital, Sri Lanka, from September to December 2024. All patients with HbE β-thalassaemia were recruited. Clinical details were collected using an interviewer schedule. Haemoglobin, ferritin and erythropoietin were measured using standard laboratory methods. Serum samples of non-thalassaemia healthy volunteers were used as controls for erythropoietin measurements. Fifty-two patients (male-42.3%; mean age 24.5 ± 13.4 years) were recruited. The mean erythropoietin of HbE β-thalassaemia patients [137 (± 127) mIU/mL] was significantly higher than that of controls [21.2 (± SD16.3) mIU/mL, p < 0.001]. Among HbE β-thalassaemia patients, erythropoietin showed a gradual and significant decline with age (r = - 0.34, p < 0.05) irrespective of the haemoglobin level. Patients who underwent splenectomy had a significantly lower median erythropoietin level compared to those who did not (40 vs. 129 mIU/mL, p < 0.001). Patients with haemolysis and anaemia-related complications, especially gallstones, had significantly lower median erythropoietin level compared to those without (69.2 vs. 125.9 mIU/mL, p = 0.039). Erythropoietin response in HbE β-thalassaemia decreased gradually with age, irrespective of the degree of anaemia. Splenectomised patients had significantly lower erythropoietin levels compared to non-splenectomised patients. Lower erythropoietin level, which could be due to age-related decline or splenectomy, was positively associated with a high prevalence of haemolysis and anaemia-related complications.