The role of IGF1 in determining body composition in children and adolescents with growth hormone deficiency and those with idiopathic short stature.

Purpose: Treatment with recombinant human growth hormone (rhGH) increases insulin growth factor-1 (IGF1) levels, therefore, monitoring both IGF1 and growth constitutes an acceptable parameter of therapeutic safety and efficacy. We aimed to investigate the relationship between IGF1 level and body composition in children and adolescents undergoing rhGH therapy for growth hormone deficiency (GHD) and idiopathic short stature (ISS).

Methods: This observational retrospective study included the bioimpedance analysis (BIA) reports (n = 305) of 135 pediatric patients (age 5-18 years), 64 with GHD and 71 with ISS, conducted as part of routine clinic visits. Sociodemographic and clinical data were extracted from medical records. Generalized estimating equations linear models were used to explore the contributing factors for body composition components of fat percentage (FATP), appendicular skeletal muscle mass (ASMM) z-score, and muscle-to-fat ratio (MFR) z-score while adjusting for cumulative doses of rhGH.

Results: Subjects with GHD exhibited higher body mass index z-scores (p < 0.001), higher FATP and truncal FATP scores, lower MFR z-score, and higher diastolic blood pressure percentiles than the ISS group (p = 0.010, p = 0.027, p = 0.050, and p = 0.050, respectively). Female sex (p < 0.001) and a GHD diagnosis (p < 0.001), were major contributors to higher FATP scores; female sex (p = 0.049) and ISS diagnosis (p = 0.005) were major contributors to higher MFR z-scores; and female sex (p < 0.001), older age (p < 0.001) and higher insulin-like growth factor 1 z-scores (p = 0.021) were major contributors to higher ASMM z-scores. Socioeconomic position and cumulative rhGH dose were not significant contributors to body composition parameters.

Conclusion: Children with GHD, including those undergoing rhGH treatment, may be at risk for increased adiposity and associated metabolic implications. Sex- and age-adjusted IGF1 levels were related to muscle mass but not to adiposity. Hence, rhGH treatment aimed at increasing IGF1 levels may alleviate these effects by promoting muscle growth.