Abstract 83: Growth hormone in obese adults

Background: It is well known that the secretion of Growth Hormone (GH) is markedly reduced in obese individualscompared to age matched controls. Many central and peripheral factors have been implicated in GH suppression inobesity. In this study, we sought to know the effect of Body Mass Index (BMI) on GH secretion in obese adults. Using a cut-off of 3 ng/dl for Glucagon Stimulation Test (GST) in obese hypopituitary subjects will overdiagnose Growth Hormone Deficiency (GHD), which is important given the increasing prevalence of obesity inIndia. In this study we intended to determine the optimal peak GH cut-offs to diagnose GHD inoverweight/obese pituitary patients using the GST in South Indian population. Methods: In this hospital based cross sectional study exogenous overweight/obese subjects and overweight/obese Hypo-pituitary patientsattending the Endocrinology OPD were taken for the study. Results: Using a traditional GH peak cut-off of 3 ng/ml after GST would classify 30% (n = 3/20) of (overweight) OW/Obese subjects as GHD. Using a cut off of 1.5 ng/ml, 10% of OW/Obese subjects and 50% of hypo pituitarysubjects will be classified as GHD, when compared to 30% and 95% respectively if cutoff of 3 ng/ml is used. Conclusion: This study suggests that there is likely over diagnosis of GHD in overweight and obese individuals using currently established peak GH cut off value of 3 ng/mL for the GST. Instead, a peak GH cut-off of 1.5 ng/mL allows for preserved sensitivity with much improved specificity for the diagnosis of GHD in overweight and obese hypopituitary patients. Larger studies are needed to confirm BMI-stratified peak GH cut-off levels to define adult GHD in this population.