Iron overload in transfusion-dependent b-thalassemia patients: defining parameters of comorbidities

Background Iron overload represents a consistent and almost inevitable complication in patients with transfusion-dependent β-thalassemia. The frequently needed erythrocyte transfusions are known to be the leading source of body iron. Increased iron deposition in tissues was strongly suggested to underlie poor growth and development in transfusion-dependent β-thalassemia. This study aimed to investigate the pattern of increase in iron-overload parameters in relation to the therapeutic measures used and explore its effect on the physical growth of patients with transfusion-dependent β-thalassemia. Patients and methods The study included 60 transfusion-dependent β-thalassemia patients (median age 12.5 years, interquartile range 8-17 years) and 20 age-matched and sex-matched controls; each group was further subcategorized into less than 12-year-old and more than 12-year-old subgroups. The studied clinical parameters comprised weight and height, which were used to calculate the body mass index (BMI). Laboratory assays included complete blood counts for the assessment of pretransfusion hemoglobin, serum iron, total iron-binding capacity, ferritin, and growth differentiation factor 15 (GDF15), and the calculation of the transferrin iron saturation percentage (TISP). Results Less than one-third (30%) of the patients had a low BMI; no patient was overweight or obese. The median pretransfusion hemoglobin was 7.1 g/dl (interquartile range 6.8-7.2 g/dl). Fifty-two (86.7%) patients were inadequately chelated, showing serum ferritin levels more than 1000 ng/ml. In patients older than 12 years of age, the BMI was significantly lower in comparison with controls of the same age subgroup as well as patients less than 12 years old. Patients with a low BMI had significantly higher median values of TISP, ferritin, and GDF15 than those with a normal BMI. GDF15 values of the more than 12-year-old patients showed significant positive correlations with TISP and ferritin levels. Setting optimal cutoffs at 63% for TISP and 1210 ng/ml for serum ferritin (area under the curve 0.965 and 0.957, respectively) had indicated low BMI with higher certainties compared with GDF15 at a level of 10 000 pg/ml (area under the curve 0.783) in the more than 12-year-old patients. Conclusion Avoiding iron overload should be warranted for transfusion-dependent β-thalassemia patients to have normal BMI. Although a high GDF15 level is helpful in pointing toward the development of a low BMI, it added no value to TISP or ferritin as indictors of patients growth retardation.