Abstract
Obesity has been associated with reduced growth hormone (GH) secretion, which might lead to the over diagnosis of adult GH deficiency (GHD) in overweight (OW)/obese hypopituitary patients. Currently, there are no body mass index (BMI)-specific peak GH cut-offs for the glucagon stimulation test (GST) for assessing adult GHD in India, given the BMI cut-offs vary for Asians. The study's main objective was to determine a peak GH cut-off level for the diagnosis of adult GHD in overweight (OW)/obese individuals utilizing the GST. Forty OW/obese subjects were studied in two groups of 20 each. The first group included 20 OW/obese hypopituitary adults and the second group included 20 control subjects. The intervention consisted of a 3 h GST. The main outcome measured was the peak GH level on GST. The mean age of control subjects was lower (33.15 ± 7.67 v/s. 42.10 ± 13.70 years; P = 0.017) in comparison with hypopituitary adults. The mean BMI (27.93 ± 1.63 v/s. 25.81 ± 1.66 kg/m2; P < 0.001), mean IGF1 (272.81 ± 38.57 v/s. 163.75 ± 42.42; P < 0.001, and mean HOMA IR (11.8 ± 9.7 v/s. 6.02 ± 3.14; P = 0.02) was greater in OW/obese controls. The mean GH peak was significantly higher in control subjects (5.41 ± 3.59 ng/mL v/s. 1.49 ± 1.25 ng/mL; P < 0.001) compared to hypopituitary subjects. ROC curve analysis demonstrated a GH cut-off of 3.3 ng/mL with a moderate sensitivity of 70% and high specificity of 95%, with an AUC of 0.838 (P < 0.001; 95% confidence interval [CI] of 0.710-0.965) for the diagnosis of GHD in overweight/obese hypopituitary adults. This study demonstrates that a cut-off of 3.3 ng/mL would diagnose GHD in Indian overweight/obese hypopituitary adults.