Predictive Factors of Persistent Growth Hormone Deficiency and Impact on Final Height

Background/Objectives: Recombinant growth hormone (rhGH) treatment plays an important role in the transition phase in those subjects diagnosed as having persistent growth hormone deficiency (GHD). We aimed to identify the main predictors of persistent GHD in a large cohort of subjects with childhood-onset GHD who underwent retesting and their correlation with height gain and mid-parental height (MPH). Methods: Anthropometric data, such as growth rate; bone age (BA); IGF-1 SDS at the start, at 1 year, and at the end of rhGH therapy; GH peak at diagnosis and at retesting; brain Magnetic Resonance Imaging (MRI) at diagnosis; and height gain upon reaching final height (FH) and compared to MPH, were obtained from medical records of GHD patients. Results: Persistent GHD was detected in 37 out of 91 (40.7%) GHD subjects. In univariate analysis, persistent GHD was associated with growth rate at 1 year (p = 0.0117) and with the first test GH peak (p = 0.0290). In the regression analysis, persistent GHD was positively associated with growth rate at 1 year (p = 0.0294) and negatively with female gender (p = 0.0424). Height gain was positively associated with growth rate (p = 0.0010) and with age at onset (p = 0.0021), while an inverse association with BA at baseline (p = 0.0002) and IGF-1 SDS (p = 0.0321) was found. Conclusions: Our study confirmed that the most important predictor of persistent GHD is the growth rate in the first year of therapy. Furthermore, growth rate in the first year, female gender, and lower BA at diagnosis are predictors of rhGH efficacy both in terms of height gain and target height achievement.