The Influence of Gonadotropin-Releasing Hormone Agonist Treatment on Thyroid Function Tests in Children with Central Idiopathic Precocious Puberty

INTRODUCTION: In recent years, the treatment of idiopathic central precocious puberty using gonadotropin-releasing hormone agonist (GnRH) agonist has been considered as a common treatment. To date, there is not much information about the effect of GnRH agonist treatment on pediatric thyroid function. AIM: The aim of this study was to evaluate the influence of GnRH treatment on thyroid function tests in children with central idiopathic precocious puberty. MATERIAL AND METHODS: This cross-sectional study investigated 50 children with idiopathic precocious puberty treated with GnRH agonist, who were referred to Bahrami pediatric hospital, Tehran, Iran. Patients` height, weight, and symptoms of hypothyroidism were evaluated every two months. Thyroid function tests, T4 and thyroid-stimulating hormone (TSH), were reviewed every 6 months. Data were analyzed using SPSS Statistics, Version 18. RESULTS: The majority of the children who participate in this study were female. 72% of children with central idiopathic precocious puberty had a significant increase in TSH level (P=0.002). In this group of patients, 66% and 6% had subclinical and clinical increases in thyroid function tests, respectively. The estimated time to thyroid dysfunction was 12.37 months. It is found that only 2% of patients showed thyroid dysfunction during the first 6 months of the treatment. CONCLUSION: The results of this study showed that more than 70% of children who were undergoing GnRH agonist treatment for central precocious puberty had impaired thyroid function (especially subclinical hypothyroidism). Therefore, evaluating thyroid function in children with precocious puberty who are under treating with GnRH agonist, would be reasonable; especially one year after initiating the treatment.