Precocius puberty and body composition: Effects of GnRH analog treatment

Introduction: Body composition changes with age and sex differences become significant only after puberty. Boys and girls before the age of 8 yr do no t differ in fat, lean or bone mineral mass. Hormonal influences during pube rtal development determine the physiological adult male and female body com position phenotype, Aim: The aim of our study was to evaluate body composition changes due to c entral precocious puberty (PP) and the specific effects of therapy on these modifications. Subjects and methods: Sixteen patients (14 girls, 2 boys) were included in the study, They were diagnosed as affected by idiopathic PP according to st andard hormonal and clinical criteria; anatomic alterations of hypothalamus -hypophysis region were excluded by MRI, Mean age at diagnosis was 5.9 +/- 1.9 yr, All patients received GnRH analog (Leuprolide or Triptorelin) treat ment subcutaneously every 4 weeks for at least 1 yr, Mean period of treatme nt was 3.4 +/- 1.9 yr, Standard anthropometry and body composition analysis were performed at baseline and every 6-12 months. A group of healthy subje cts with normal timing of puberty was matched (for age or for pubertal stag e) sewed as the control group (CA or CP, respectively). Results: Patients with PP showed at baseline a significant increase of BMI and relative body weight; lean and fat compartments were also increased but not significantly, During treatment, the PP group showed increased fat mas s compared to CA (p<0.05), while no difference was found between PP and CP, Lean mass was similar to CA but lower than in CP (p<0.05), During treatmen t a significant increase in lean mass (both as total as well as limb mass) was observed. After stopping treatment there was no difference between PP a nd CP, except for lower lean mass (p<0.04), Conclusion: When puberty occurs precociously, lean and fat mass are not sig nificantly different from age-matched control subjects. Data collected duri ng treatment confirm a shortening of prepubertal lean mass development and the block of further lean mass development due to puberty itself, while fat mass accumulation continues. The net result of these modifications determi nes a typical body composition pattern in PP patients, after the end of the rapy: lean mass is reduced by a shortening of the prepubertal growing perio d and by the "menopausal effect" of treatment itself, Fat mass is increased as a consequence of therapy and could lead to future obesity.