NS-18: ROLE OF METFORMIN IN THE TREATMENT OF HYPOTHALAMIC OBESITY SYNDROME (HOS)

BACKGROUND: HOS in children with structural hypothalamic lesions is characterised by weight gain refractory to standard lifestyle interventions. Disruption of hypothalamic function results in hyperphagia, hyperinsulinemia and possible reduction of energy expenditure. Metformin induces anorectic effects, but its role in these patients has not been studied. OBJECTIVE: To compare BMI of patients with HOS before and after treatment with Metformin. METHOD: BMI of 6 children with HOS unresponsive to demonstrable change in lifestyle measures was compared before and after treatment with metformin by converting BMI to BMI standard deviation scores (SDS). Tolerance to metformin was assessed. RESULTS: There were 6 females. [Hypothalamic hamartoma (N = 2), craniopharyngioma (N = 2), hypothalamic astrocytoma (N = 2)]. Treatment included surgery (N = 5), primary fractionated radiotherapy (N = 1), additional proton beam radiotherapy (N = 1) and chemotherapy (N = 1). Results are given as median (range). Age at diagnosis was 10.1years (1.3-13.8). Metformin was introduced at 12.5years of age (4.5-18.1). The change in BMI SDS was +0.42/year (+0.06 to +3.6) after 4.3 years (0.2 to 7.1). The change in BMI SDS between commencement of metformin and the final assessment was +0.15/year (-0.31 to +0.22) after follow up of 1.9 years (1.3-5.4). The rate of change in BMI SDS before and after introduction of metformin is statistically significant (p= 0.043). CONCLUSION: Use of metformin in addition to lifestyle change is associated with control of obesity in patients with HOS and structural disease where lifestyle change alone was not successful. A prospective study is warranted to rigorously examine its role in this difficult group of patients.