Thyroid function changes during growth hormone therapy in pediatric patients: a controlled study and review of recent data

Introduction: Growth hormone therapy is a cornerstone treatment for children with GHD and ISS. Its impact on the hypothalamic-pituitary-thyroid axis, however, has been a subject of ongoing research. This review compiles findings from several studies spanning three decades and contrasts them with recent data to enhance our understanding of thyroid function dynamics during GH therapy. Review of Literature: Early Observations (1992-2005) Pirazzoli et al. (1992) and Tang et al. (1997) were among the first to document changes in thyroid function due to GH therapy, noting enhanced peripheral conversion of T4 to T3 and a prevalence of subclinical hypothyroidism. Wyatt et al. (1998) reported significant decreases in T4 and increases in T3, indicating a notable shift in thyroid hormone levels early in GH therapy. Mid-Term Studies (2005-2015) Seminara et al. (2005) and Kalina-Faska et al. (2004) reported changes in thyroid function, particularly a decrease in T4 levels and a transient increase in fT3 during the early stages of GH therapy. · Recent Developments (2016-Present) Wang Ying and Liang Furong (2016) emphasized the need for vigilant monitoring of thyroid hormone levels, aligning with Zheng et al. (2014) who noted improvements in lipid metabolism without significant thyroid function impacts. Glynn et al. (2017, 2018) and Kucharska et al. (2021) focused on the complexities of the biological effects of GH-induced changes in thyroid hormones. Comparison with our Data Our recent study reveals subtle changes in thyroid function in GH-treated children with GHD and ISS. We observed a slight decrease in mean FT4 and an increase in mean TSH in the GH treatment group, stable TSH and decreased FT4 in the ISS treatment group, and significant decreases in both FT4 and TSH in the no-treatment group. These findings corroborate the trend seen in earlier studies, highlighting the multifaceted nature of thyroid function changes during GH therapy. Conclusions: The review underscores that GH therapy can significantly influence thyroid function, necessitating regular monitoring of thyroid hormone levels. The variation in thyroid responses suggests a complex interaction between GH therapy and the hypothalamic-pituitary-thyroid axis, which may be influenced by factors like age, severity of GHD, and duration of GH treatment.