ESPE Abstracts

Background: Children born SGA have been implicated to be at higher risk for subsequent obesity; however, the body composition, especially fat distribution, in SGS short stature (SGA-SS) patients and the effects of growth hormone (GH) therapy on body composition in SGA-SS have not been fully studied.

Purpose: To unravel the effects of GH therapy on body fat mass, body fat distribution, muscle mass, and bone mineral density (BMD) in SGA-SS.

Method: Thirty pre-pubertal subjects with SGA-SS (14 boys and 16 girls, mean age at GH commencement 4.1+/- 1.1 years old) were included. Data on cumulative dose of GH, height (HT)-SDS, BMI-SDS, IGF-1 SDS, body composition by DXA analysis, and fat distribution by abdominal CT analysis obtained before and 1-year after GH treatment were retrospectively evaluated based on medical records. Parameters of body composition included percent fat mass (%FM) and percent muscle mass (%MM). Bone size-corrected volumetric lumbar BMD (vBMD) was calculated. Statistical analysis was performed using paired t-test or Pearson's correlation analysis. This study was approved by the institutional ethical committee.

Results: HT-SDS prior to GH treatment (Pre-HT-SDS) was -2.75 +/- 0.43 SD and this was not associated with IGF-1 SDS or BMI-SDS. However, Pre-HT-SDS was positively and negatively associated with %MM)(r=0.59, P<0.001) and %FM(r=-0.58, P<0.001), respectively. vBMD showed no association with Pre-HT-SDS. Abdominal CT revealed that amounts of visceral (VAT) and subcutaneous adipose tissue (SAT) were not elevated (VAT 4.22cm², SAT 11.36 cm²). These findings suggest that impaired acquirement of muscle mass may be pathogenically associated with the development of SGA-SS. Upon 1-year GH treatment, HT-SDS and IGF-1 SDS increased significantly, although ΔHT-SDS was not associated with ΔIGF-1 SDS. Cumulative GH dose showed weak association with ΔHT-SDS (r=0.38, P<0.05). %FM significantly decreased by GH treatment, whereas GH treatment significantly increased %MM and vBMD. Abdominal CT showed that the amount of VAT slightly increased after GH therapy (5.32 cm²), but the value still resided within the normal reference levels. Amount of SAT was not affected (9.36 cm²). These results suggest that decreases in %FM by GH treatment was mainly caused by increases in muscle mass and bone mineral density.

Conclusion: GH therapy in children with SGA-SS increased HT-SDS and this was associated with improvement of body composition by increasing muscle mass and bone mineral density rather than reducing fat mass.