Aristeidis Giannakopoulos, Maria Tsanti, Ioannis Amplianitis, Alexandra Efthymiadou, Dionysios Chrysis
The findings of our study are consistent with most previous studies, confirming that rGH therapy in GHD children induces a modest, statistically significant decline in FT4 while maintaining stable TSH. FT4 was associated with the increase of IGF-1 SDS during rGH therapy while the addition of SPINA-GT evaluation supports the preservation of the thyroid secretory reserve during the first year of rGH treatment.
OBJECTIVE: GH/ IGF-1 and thyroid axes are interconnected. Previous studies reported mixed findings regarding the effect of rGH therapy on thyroid function in children with GH deficiency. This study aimed to investigate longitudinal thyroid function changes over the first year of rGH therapy and assess the secretory capacity of the thyroid gland, using the Structure Parameter Inference Approach (SPINA-GT).
METHODS: Prospective longitudinal cohort study in a single tertiary centre.
RESULTS: One-hundred-eleven children with idiopathic GH deficiency were treated with rGH (0.22 mg/kg/week). Baseline median age was 10.0 years, with 84% being prepubertal. After 12 months of rGH therapy, IGF-1 levels significantly increased (p<0.001), while FT4 levels modestly declined (p=0.008). TSH and SPINA-GT index did not show significant changes. Mixed-effects modelling analysis revealed association of FT4 with IGF-1 standard deviation score (SDS) (p<0.001), whereas TSH was not associated with any covariate.
CONCLUSION: The findings of our study are consistent with most previous studies, confirming that rGH therapy in GHD children induces a modest, statistically significant decline in FT4 while maintaining stable TSH. FT4 was associated with the increase of IGF-1 SDS during rGH therapy while the addition of SPINA-GT evaluation supports the preservation of the thyroid secretory reserve during the first year of rGH treatment.