Introduction: Proportional short stature is one of the most important features of Noonan Syndrome, and adult height often remains below the 3rd percentile. Although the pathophysiology of short stature in NS patients is not fully understood, it has been shown that GH treatment is beneficial in NS, and it significantly improves the height in respect to the results of short and long-term GH treatment. Methods: In this study, the efficacy of GH therapy was evaluated in children and adolescents with Noonan syndrome who attained final height. In this national cohort study, 67 cases with NS who reached final height from 14 centers were evaluated. Results: A total of 53 cases (mean follow-up time 5.6 years) received GH treatment. Height SDS of the subjects who were started on GH tended to be shorter than those who did not receive GH (-3.26± 1.07 vs. -2.53 ±1.23) at initial presentation. The mean final height and final height SDS in girls using GH vs those not using GH were 150.1 cm and -2.17 SD vs 47.4 cm and-2.8 SD, respectively. The mean final height and final height SDS in boys using GH vs. not using GH were 162.48 ± 6.19 cm and -1.81 SD vs 157.46 ± 10.16 cm and -2.68 ± 1.42 SD, respectively. The Δheight SDS value of the cases was significantly higher in the group receiving GH than in those not receiving GH (1.36 ± 1.12 SD vs. -0.2 ± 1.24, p<0.001). Cardiac findings remained stable in two patients with hypertrophic cardiomyopathy who received GH treatment. No significant side effects were observed in the cases during follow-up. Conclusion: In patients with Noonan syndrome who reach their final height, a significant increase in height is observed with GH treatment, and an increase of approximately +1.4 SDS can be achieved. It has been concluded that GH treatment is safe and effective.
