Birth weight influences long-term catch-up growth and height prognosis of GH-deficient children treated before the age of 2 years

Objective: To investigate which pretreatment variables most significantly affect long-term growth response to GH therapy in children with apparently idiopathic GH deficiency (GHD) treated from a similar and very young age (less than 2 years), for the same period (7 years) and with the same therapeutic protocol. Design and methods: Twelve children with either isolated GHD or multiple pituitary hormone deficiency were treated with biosynthetic human GH (0.7 IU/kg per week) and were examined every 6 months. Height measurements were performed by Harpenden stadiometers. Bone age was evaluated every 12 months. Results: The onset of therapy was followed in all patients by an important height gain, which attained its zenith during the first year of treatment and became progressively less evident during the next 4 years. Cumulative height gain was 3.0 ± 1.7 SDS. Thanks to the therapy, at the end of the 7-year treatment period, average height in the entire series was not significantly far from mean target height (TH) (-0.7 ± 1.3 vs -0.3 ± 0.4 SDS) and average predicted height (PH) (-0.2 ± 1.4 SDS) was very close to TH. A stepwise regression analysis showed that both catch-up growth under therapy and PH at the end of the 7-year treatment period were positively influenced by birth weight (BW). Conclusions: a) Our 7-year prospective study on GHD infants treated with GH from less than 2 years of age confirmed the importance of early diagnosis and treatment of GHD in childhood. b) The influence of BW on growth response to GH therapy in GHD children persists over time, at least when treatment is begun from less than 2 years of age.