Serum ghrelin levels are inversely correlated with body mass index, age, and insulin concentrations in normal children and are markedly increased in Prader-Willi syndrome. - Haqq,A.M.; Farooqi,I.S.; O'Rahilly,S.; Stadler,D.D.; Rosenfeld,R.G.; Pratt,K.L.; LaFranchi,S.H.; Purnell,J.Q. (J Clin Endocrinol Metab, 2003)