Thyroid Status in Children with Transfusion Dependent Hb-E β-Thalassaemia

Despite improved haematological care, multi-endocrine dysfunction is a common complication in thalassemia. Iron overload is thought to be the most likely mechanism in thyroid dysfunction in these patients. Moreover, chronic tissue hypoxia might havedirect toxic effect on thyroid gland resulting in hypothyroidism. This study was designed to evaluate the thyroid status of children with Hb-E β-thalassemia. This cross sectional analytic study was conducted among thepatients with Hb-E β-thalassemia attending both in-patient & out-patient department of Paediatrics, Dhaka Medical College & Hospital, Dhaka, Bangladesh from April 2012 to March 2013. The children who attended inpatient and outpatient department of Paediatrics for some other illness were screened out for thalassaemia and were recruited as comparison group. Thyroid function tests (TSH & FT₄ level) were performed in both thalassaemic patients and comparison group. Serum ferritin level was also measured for assessing iron status of thalassaemic patients and their pre-transfusion Hb levels were recorded in the pre-formed data collection form. Of the 50 thalassaemia patients, 13(26%) had subclinical hypothyroidism. This proportion of subclinical hypothyroidism was significantly high, compared to that (2.5%) of non thalassaemia comparison group. Among the subclinically hypothyroid thalassaemia subjects, 8 were males and 5 were females and their mean age was 102.38±33.29 months. The mean serum ferritin levels in hypothyroid and euthyroid thalassaemia cases were 2387.87±1642.85ng/ml and 1822.95±1345.33ng/ml respectively (normal level upto 300ng/ml). This difference was not statistically significant (p=0.279); but the pre-transfusion Hb level wasfound significantly different (p=0.02) among the two groups. It was 5.57±0.98g/dl in hypothyroid & 6.37±0.09g/dl in euthyroid thalassaemic cases. Subclinical hypothyroidism was quite high among the children with transfusion dependent Hb-E β-thalassaemia. Their hypothyroid status had no significant correlation with their serum ferritin level but had significant correlation with low haemoglobin status.