Hyperleptinaemia in young adults following cranial irradiation in childhood: growth hormone deficiency or leptin insensitivity?

OBJECTIVE In order to explore the mechanism of obesity in long‐term survivors of childhood leukaemia, fat mass, lean body mass and serum leptin were assessed in a cohort of 32 (17 males) adults who had received cranial irradiation (XRT) in childhood as part of their treatment for acute lymphoblastic leukaemia (ALL), and compared with 35 age and body mass index (BMI) matched young adults (18 male). DESIGN Thirty‐one patients and 18 controls had fat mass and lean body mass assessed by dual x‐ray absorptiometry (DEXA), using a lunar DPX‐L scanner. Serum leptin concentrations were also measured in 27 patients and all controls. Growth hormone status had previously been determined using an insulin tolerance test and arginine stimulation test. Nine patients were classified as severe growth hormone (GH) deficient (group 1), 12 patients as GH insufficient (group 2) and 11 patients as normal (group 3). RESULTS BMI and absolute fat mass were not significantly different between the patients and controls regardless of their gender (P = 0.1 and P = 0.14 respectively). In contrast, absolute lean mass was significantly reduced (P