Assessing the predictive value of the suppressed 1 mg overnight dexamethasone suppression test in success of bariatric surgery

Bariatric surgery has been proven to be a successful intervention for managing obesity. There are numerous studies in the literature aiming to predict the factors influencing the success of bariatric surgery. Our study aims to determine whether preoperative 1 mg overnight dexamethasone suppression test (1 mg-DST) serum cortisol levels can serve as predictors of the effectiveness of bariatric surgery in severe obese patients without Cushing syndrome. A total of 98 patients who underwent bariatric surgery were included in the study. The preoperative 1 mg-DST levels, insulin levels, thyroid function tests, and lipid profiles of the patients were recorded. The patients' preoperative, postoperative 3rd, and 6th month weights were recorded and the percent total weight loss (%TWL) is calculated. Patients were categorized into 2 groups based on their TWL at 6 months. The 1 mg-DST results were significantly lower in the high-TWL-6 group (0.93 ± 0.37 μg/dL) compared to the low-TWL-6 group (1.09 ± 0.36 μg/dL, P = .040). Similarly, Homeostatic Model Assessment for Insulin Resistance values were lower in the high-TWL-6 group (5.63 ± 2.21) compared to the low-TWL-6 group (6.63 ± 2.55, P = .047). The optimal cutoff value found for 1 mg-DST level was 0.97 µg/dL, providing 50% sensitivity and 70% specificity. This study is the first to examine the predictive role of suppressed 1 mg-DST levels on postoperative weight loss in nondiabetic patients. The most prominent result of this study was that we observed a negative correlation between 1 mg-DST levels and %TWL.