EVALUATION OF PRE-PRANDIAL AND POSTPRANDIAL GROWTH-HORMONE (GH)-RELEASING HORMONE-INDUCED GH RESPONSE IN SUBJECTS WITH PERSISTENT BODY-WEIGHT NORMALIZATION AFTER BILIOPANCREATIC DIVERSION

BACKGROUND: Obesity is characterised by growth hormone (GH) abnormalit ies, including a blunted response to stimulation and a 'paradoxical' i ncrease after meals. The blunted GH release is reversed by a surgical intestinal bypass procedure. However, this does not mean that normal G H dynamics have been restored. The present study assessed whether post -surgical weight reduction in obese patients normalised the modulation of GH release produced by metabolic fuels. SUBJECTS: Ten obese female subjects, aged 23-54y, were studied before and after biliopancreatic diversion (BPD). All patients, after surgery, had experienced a signif icant reduction in body weight (mean body mass index (BMI) 25.78 +/- 1 .01 kg/m(2) vs 44.68 +/- 1.73 kg/m(2)). Two groups were also studied a s controls: Ten normal body weight female subjects and ten patients su ffering from anorexia nervosa (AN, mean BMI 17.46 +/- 1.12 kg/m(2)). M EASUREMENTS: We have studied the GH response to a GH releasing hormone (GHRH) bolus (1 mu g/kg iv, at 13.00 h) before and after a standard m eal. RESULTS: In post-BPD subjects, the GH response to GHRH in the fas ting state, was clearly augmented in comparison with the pre-BPD value s (peak values 18.06 +/-4.56 vs 3.24+/-0.68 mu g/L). In post-BPD subje cts the postprandial GH response was further augmented in comparison w ith the fasting test (peak 30.12 +/- 4.99 mu g/L, P < 0.05). This patt ern was similar to that observed in anorexic patients. CONCLUSION: The surgical procedure restores a normal GH response to GHRH in the fasti ng state, but the 'paradoxical' GH response after meals remains presen t, suggesting a persistent GH derangement in such patients, which is n ot related to body weight per se. The surgical procedure makes obese p atients similar to anorexics, in the relationships between metabolic f uels and GH secretion. The persistence of the GH postprandial response to GHRH in post-BED subjects suggests a role for metabolic fuels in t he regulation of somatostatin (SRIF) secretion.