Diagnostic re-evaluation of children with congenital hypothyroidism.

OBJECTIVES To investigate the causes of congenital hypothyroidism in children more than 3 years of age and to document the frequency of transient vs permanent hypothyroidism. DESIGN Hospital based observational study. SETTING Pediatric endocrine clinic of a medical college. PATIENTS Children over 3 years of age, on treatment for congenital hypothyroidism. INTERVENTION Thyroid function test (TFT) and thyroid ultrasound was done. Children with agenesis or hemiagenesis in thyroid ultrasound were identified. In children with normal or equivocal thyroid ultrasound, thyroxine was stopped and followed. Children with abnormal TFT on follow up had thyroid scintigraphy with or without potassium perchlorate discharge, after which, thyroid hormone supplement was restarted. Children who remained euthyroid on follow up were labeled as having transient hypothyroidism. MAIN OUTCOME MEASURE Proportion of children with transient hypothyroidism. RESULTS Among 36 children studied (20 boys and 16 girls), eighteen (50%) had transient hypothyroidism and fifteen (41.7%) had thyroid agenesis. There was one with hemiagenesis, one with ectopic thyroid and another with dyshormonogenesis (2.8% each). Initial TSH level at the time of diagnosis was higher in permanent hypothyroidism as compared with transient group (83.0 ± 31.6 vs 47.0 ± 33.1 mIU/mL; P= 0.002). CONCLUSIONS Thyroid hormone supplementation could be discontinued in 50% of children diagnosed with congenital hypothyroidism.