ESPE Abstracts

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. Some studies have demonstrated a relationship between hypothyroidism and SCA with a prevalence of 6% in children and adolescents. Hypothyroidism may affect brain and physical development.

Objective: This study aimed to determine the prevalence and factors associated with hypothyroidism among children with SCA attending the Sickle Cell Clinic (SCC), Mulago hospital.

Methods: A cross-sectional study of children aged 6 months -17 years with a confirmed diagnosis of SCA, no prior diagnosis of hypothyroidism and in their steady state attending the SCC in Mulago hospital was conducted. 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], and sub-clinical hypothyroidism as TSH ranging between 4.5 and10 mIU/l with normal age appropriate free T4 levels that is: 6-11 months [0.9-2.0ng/dl]; 1-5years [1.0-1.8ng/dl];6-10 years [1.0-1.7ng/dl] and 11-17 years [1.0-1.6 ng/dl]. Multivariate logistic regression models were constructed to determine the factors associated with hypothyroidism. A P< 0.05 was considered as significant.

Results: Of the 332 children enrolled, 50.3% (167/332) were female; their median age (IQR) was 6 (3-10) years. Sixty (18.1%) participants had hypothyroidism (95% CI: 14.3 — 22.6) of whom all had sub-clinical hypothyroidism. The factors associated with hypothyroidism were 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.