: Growth hormone excess (GHE) in children with neurofibromatosis type 1 (NF-1) has been reported in some cases. The prevalence of GHE in NF-1 has not been described and treatment with long-acting somatostatin analogues (SSA) has not been well characterized.

Objective: To describe in children with NF-1/OPG the prevalence of GHE, and response to SSA.

Results: From 379 children with NF-1, 80 were diagnosed of OPG (21%). In a prospective follow up 8.7% were identified as having GHE; all were prepubertal, with a mean age of 4.4±1.9 years. The mean height was + 0.86 ± 0.76 SD above the mid parental height; growth velocity +4.07 SD, mean IGF-1 > 1SD (457.8±151.3 ng/mL). In 4 patients the GHE was observed during tumor progression. The first two patients were initially treated with short- acting somatostatin analogues (SSA) (1.5 μg/kg/day). After confirming tolerability, it was replaced by long- acting somatostatin analogues (SSA) (10 mg/28 days). Four were initially treated with (10 mg/28 d). 6/7 patients showed a normalization of IGF-1 and growth velocity. Treatment could be withdrawn in all patients after 19.9 ± 4.6 months. The patients remained stable for 48 months (24-60). Except for mild diarrhea, no other adverse events were observed.

Conclusions: We should consider the risk GHE in patients with NF-1-OPG, as this may be a cause for concern indicating tumour progression. Treatment with long-acting somatostatin analogues (SSA) was effective and safe. After treatment, the patients' growth and analytical parameters remained within normal range, confirming the reversibility of growth hormone excess.