IGF1 and Prader-Willi syndrome: The median (IQR) free IGF-I SDS in both prepubertal and pubertal children with PWS was significantly lower than the 0 SDS (p < 0.001), being −0.4 (−0.6 to −0.2) SDS and −0.8 (−1.0 to −0.6) SDS, respectively.