Endocrine Abstracts

Background: GH replacement during the childhood-adult transition period is important for somatic maturation. The aim of the study was to explore the factors influencing IGF1 response to GH during transition.

Methods: KIMS (Pfizer International Metabolic Study) database in UK was interrogated, and 98 patients (55 male, median age 20.7 years (15.7–25.8)) with childhood-onset GH deficiency (Co-GHD), who were started on adult dose of GH during transition (age <26 years) were identified. IGF1 SDS were estimated using age and gender specific normative data. ‘IGF1 response’ was calculated from baseline IGF1 levels prior to GH therapy, mean IGF1 levels and the corresponding GH doses from 6 to 24 months of starting treatment, using the formula: ΔIGF1 SDS/GH dose (mg/surface area).

Results: During GH treatment, mean IGF1 SDS ±S.D. of the patients increased from -2.90±1.96 to 0.054±1.79 after a median period of 12 months. However, the IGF1 levels were lower than the recommended ranges (0–2 SDS) in 43 patients (44%). In women, baseline IGF1 levels were lower (P=0.006), and was associated with a higher GH dose (P<0.001) and reduced IGF1 response (P=0.021) (Table). IGF1 response was also reduced in younger patients (r=0.29, P=0.006). Among women, oral oestrogen therapy (n=27) was associated with a higher GH dose (0.34±0.12 vs 0.24±0.09 mg/m², P=0.007), but lower IGF1 levels (−0.84±1.70 vs 0.69±1.42, P=0.004) and thus a lower IGF1 response (10.0±4.7 vs 13.8±6.7 mg/m², P=0.001). In contrast, testosterone therapy in men (n=30) was related to a higher IGF1 response (16.6±8.2 vs 9.9±5.8 mg/m², P=0.016). The number or type of other hormonal deficiencies did not affect the response to GH.

Conclusions: In this study, IGF1 response to GH during transition was evaluated in a large group of patients for the first time, and associations with age, gender and sex hormone replacement therapy were observed. Further studies are required to explore the effects of these factors on other endpoints of GH replacement during this period of somatic development.

Declaration of interest: The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.

Funding: This work was supported, however funding details unavailable.