OC-70 Are children with isolated idiopathic growth hormone deficiency and idiopathic short stature responding differently to somatropinum administration?

Introduction Traditionally, children with idiopathic short stature (ISS) are considered to be partially resistant to growth hormone (GH), being, therefore less responsive to GH administration in comparison to children with GH deficiency (GHD). Moreover, the reimbursement policy for GH administration for short stature in children state that GH should be administrated for a more severe height deficiency in ISS (below −3 SD) in comparison to GHD (−2 SD). The aim of the study was to evaluate whether children with short stature due to idiopathic isolated GHD (IGHD) respond differently to somatropinum administration in comparison to ISS children. Material and methods patients were 155 children (age 2,9–12 years, 106 male/49 female) diagnosed with ISS (32 patients) and IGHD (123 patients) and treated according to the national protocol for 3,6 years. Standard deviation scores (SDS) for height were calculated at different time points and compared between the two groups. A favourable response to treatment was considered an increase in height with at least 0,5 SD year. Results SDS for height at the first evaluation was similar between groups (mean of −3,3 for ISS and −3,1 for IGHD). A similar proportion of patients had a favourable response to treatment during follow-up (71,5% of IGHD and 71,9% of ISS children, p=NS), with a mean recovered SDS for the height of 1,56±0,4 SD in IGHD and 1,48±0,52 SD in ISS group (p=NS). No statistically significant differences between the two groups were observed for the gain in SDS for height at 6, 12, 18 and 24 months of follow-up, the highest response occurring in the first 18 months. The doses of somatropinum administered were not statistically different in the two groups. Conclusion our study showed that the responsiveness to somatropinum administration is similar in patients with ISS and IGHD diagnosed based on current GH cut-offs. Therefore, readjustment of height deficit criteria for GH administration for these two categories of patients should be taken into consideration in order to improve cost efficiency.