title: Comparison of 1 mg and 2 mg overnight dexamethasone suppression tests for the screening of Cushing's syndrome in obese patients.
abstract: OBJECTIVE
  Obesity is currently a major public health problem and one of the potential underlying causes of obesity in a minority of patients is Cushing's syndrome (CS). Traditionally, the gold standard screening test for CS is 1 mg dexamethasone overnight suppression test. However, it is known that obese subjects have high false positive results with this test.
  
  
  METHODS
  We have therefore compared the 1 mg and 2 mg overnight dexamethasone suppression tests in obese subjects. Patients whose serum cortisol after ODST was >50 nM underwent and a low-dose dexamethasone suppression test (LDDST); 24-hour urine cortisol was collected for basal urinary free cortisol (UFC). For positive results after overnight 1-mg dexamethasone suppression test we also performed the overnight 2-mg dexamethasone suppression test.
  
  
  METHODS
  We prospectively evaluated 100 patients (22 men and 78 women, ranging in age from 17 to 73 years with a body mass index (BMI) >30 kg/m2 who had been referred to our hospital-affiliated endocrine clinic because of simple obesity. Suppression of serum cortisol to <50 nM (1.8 microg/dL) after dexamethasone administration was chosen as the cut-off point for normal suppression.
  
  
  METHODS
  Thyroid function tests, lipid profiles, homocysteine, antithyroglobulin, anti-thyroid peroxidase antibody levels, vitamin B12, folate levels, insulin resistance [by homeostasis model assessment (HOMA)] and 1.0 mg postdexamethasone (postdex) suppression cortisol levels were measured.
  
  
  RESULTS
  We found an 8% false-positive rate in 1 mg overnight test and 2% in 2 mg overnight test (p=0.001). There was no correlation between the cortisol levels after ODST and other parameters.
  
  
  CONCLUSIONS
  Our results indicate that the 2 mg overnight dexamethasone suppression test (ODST) is more convenient and accurate than 1-mg ODST as a screening test for excluding CS in subjects with simple obesity.
authors.affiliation: Department of Endocrinology and Metabolism, Gulhane School of Medicine, Etlik, Ankara, Turkey. drsahinmustafa@yahoo.com
authors.forename: Mustafa
authors.initials: M
authors.lastname: Sahin
authors.forename: Levent
authors.initials: L
authors.lastname: Kebapcilar
authors.forename: Abdullah
authors.initials: A
authors.lastname: Taslipinar
authors.forename: Omer
authors.initials: O
authors.lastname: Azal
authors.forename: Taner
authors.initials: T
authors.lastname: Ozgurtas
authors.forename: Ahmet
authors.initials: A
authors.lastname: Corakci
authors.forename: Emin Ozgur
authors.initials: EO
authors.lastname: Akgul
authors.forename: Mine Yavuz
authors.initials: MY
authors.lastname: Taslipinar
authors.forename: Mahmut
authors.initials: M
authors.lastname: Yazici
authors.forename: Mustafa
authors.initials: M
authors.lastname: Kutlu
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D003480:Cushing Syndrome / Q000097:blood* / Q000150:complications / Q000175:diagnosis*; D003907:Dexamethasone / Q000008:administration & dosage*; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D006854:Hydrocortisone / Q000097:blood; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000097:blood* / Q000150:complications / Q000175:diagnosis*; D011446:Prospective Studies; D013997:Time Factors; D055815:Young Adult
chemical_list: D003907:Dexamethasone; D006854:Hydrocortisone