Noonan Syndrome Patients With Short Stature At A Single Pediatric Endocrinology Centre

Introduction: Noonan syndrome (NS) is caused by mutations in RAS/MAPK signalling pathway genes. Growth hormone (GH) treatment is an established yet not fully standardized treatment. Aim: The aim of this article is to assess the first 2 years of GH treatment in NS patients at a single centre. Patients and Methods: A total of 20 (16 males) NS clinically diagnosed regularly followed patients participated (2011–2020). Of these, 9 (45%) had cardiac defects, and 8 (40%) had short stature. Growth hormone deficiency (GHD) was confirmed in 5 patients who started GH treatment, and 2 were treated as short, small for gestational age children. Patients underwent anthropometry, clinical, laboratory and imaging investigations. Results: The mean age at NS diagnosis was 7.8 ± 3.4 years (1.3 ÷ 10.5), and at GH start 9.1 ± 1.5 years. At GH start, SDS height was -3.42±0.58 (-4.1 ÷ -2.6), SDS weight -3.07 ± 0.58 (-3.73 ÷ -2.27), and SDS IGF1 -1.12 ± 0.98 (-2.44 ÷ 0.25). The mean BA at diagnosis was delayed by 2.6 ± 0.9 years. The GH starting dose was 0.035 ± 0.005 mg/kg/d, and changed little thereafter. The growth velocity for the 1 st year of treatment was 8.9 ± 1.4 cm, and for the 2 nd year 6.9±1.1 cm. The first year ΔSDS height was 0.72 (p = 0.002), ΔSDS weight was 0.83 (p = 0.025), the 2 nd year increments being insignificant. The 1 st and 2 nd year ΔSDS IGF1 were 1.70 (p = 0.007) and 0.25 (n.s.), resp. Bone age remained significantly delayed. No treatment side effects were observed. Conclusion: Our study showed that GH-treated NS patients follow the general growth patterns. In order to improve outcomes, the treatment should be further standardized.