Screening for Cushing's syndrome in obese patients; is it really necessary?

Abstract

to be more frequent among patients with metabolic syndrome. Previous studies have suggested to perform a routine screening for CS in obese patients; however, more recent reports only recommend a case-finding approach in patients with uncontrolled diabetes and hypertension, despite appropriate treatment. Objective: The aim of this study was to evaluate the prevalence of unsuspected CS in morbidly obese patients in an outpatient’s clinic. Patients and methods: Retrospective case-note study. We reviewed the medical records of morbidly obese patients referred to our clinic prior to bariatric surgery between january 2001 and december 2011. All patients had a complete medical history including physical examination, and 399 underwent screening for CS as part of our pre-surgical protocol. As screening for autonomous cortisol secretion, we performed an overnight 1 mg Dexamethasone Suppression Test (DST). Serum cortisol < 1.8 μg/dl was the cut-off point for normal suppression. Results: 399 patients (308 female; mean age 41.9 ± 10.5 years; mean BMI 51.5 ± 8.4 kg/m2). In the retrospective analysis, prediabetes and diabetes mellitus were observed in 10.3% and 27.8% respectively. In 21 of 399 patients, screening was considered to be abnormal. Eight of these 21 patients had subsequent normal 24h Urinary Free Cortisol (UFC) levels (150 μg/24h). In 13 of 20 patients, we repeated an overnight 1mg DST, on suspicion of failing to take the dexamethasone correctly. Three patients failed to suppress their cortisol levels, two of them were on carbamazepine, which was considered to be a false positive result. The other patient with abnormal UFC levels was diagnosed with CS (0.26%), whose cause was a pituitary microadenoma. Conclusion: A low proportion of patients with morbid obesity were found to have CS. Our findings suggest that morbidly obese patients should not be routinely screened for CS.