Prevalence and Factors Associated with Hypothyroidism in Children with Sickle Cell Anemia Aged 6 Months -17 Years Attending the Sickle Cell Clinic, Mulago Hospital, Uganda; A cross- sectional study

Abstract Background Sickle cell anemia (SCA) leads to chronic end organ damage including the thyroid gland. This is postulated to be due to recurrent hemolysis leading to iron overload, vaso - occlusive crises, micro-vasculature obstruction due to red cell entrapment and frequent transfusions. Hypothyroidism has been reported at a prevalence of 6% in children and adolescents with SCA. Hypothyroidism may affect brain and physical development. In this study, we determined the prevalence and factors associated with hypothyroidism among children with SCA attending the Sickle Cell Clinic (SCC), Mulago hospital in Uganda. Methods A cross-sectional study was conducted among children aged 6 months − 17 years with a confirmed diagnosis of SCA, no prior diagnosis of hypothyroidism and in steady state attending the SCC in Mulago hospital. Data was collected using a structured questionnaire and a blood sample obtained was used to measure thyroid stimulating hormone (TSH) and free thyroxine (FT4). Clinical hypothyroidism was defined as TSH level > 9 mIU/L and free T4 < 0.6 ng/dL [primary hypothyroidism] or normal or low TSH level and free T4 < 0.6 ng/dL [central hypothyroidism]. Sub-clinical hypothyroidism was TSH ranging between 4.5 and10 mIU/L with normal age appropriate free T4 levels. Multivariate logistic regression models were constructed to determine the factors associated with hypothyroidism. A p < 0.05 was considered significant. Results Of the 332 children enrolled, 50.3% (167/332) were female; median age (IQR) was 6 (3–10) years. Sixty (18.1%) participants had hypothyroidism (95% CI: 14.3 — 22.6) and all the 60 had sub-clinical hypothyroidism. Factors associated with hypothyroidism included constipation [aOR: 3.1, 95% CI:1.0 — 9.0, p = 0.043] and male sex [aOR:2.0, 95% CI:1.1— 3.5, p = 0.025]. Conclusions Approximately 1 in 5 children (18.1%) had hypothyroidism. Males and children who presented with constipation were more likely to have hypothyroidism. This suggests that clinicians should screen all children with SCA who present with constipation for hypothyroidism and those found with hypothyroidism should be treated appropriately to improve their growth and quality of life.