Horm Metab Res 2010; 42(4): 280-284
DOI: 10.1055/s-0029-1246191
Humans, Clinical

© Georg Thieme Verlag KG Stuttgart · New York

Screening for Subclinical Cushing's Syndrome in Type 2 Diabetes Mellitus: Low False-Positive Rates with Nocturnal Salivary Cortisol

L. Gagliardi1 , 2 , I. M. Chapman1 , 2 , P. O’Loughlin3 , D. J. Torpy1 , 2
  • 1School of Medicine, University of Adelaide, Adelaide, South Australia, Australia
  • 2Endocrine and Metabolic Unit, Royal Adelaide Hospital, North Terrace, Adelaide, South Australia, Australia
  • 3Endocrine Laboratory, SA Pathology, Adelaide, South Australia, Australia
Further Information

Publication History

received 13.11.2009

accepted 22.12.2009

Publication Date:
29 January 2010 (online)

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Abstract

The diagnosis of subclinical Cushing's syndrome (SCS) is important, but its relative rarity amongst patients with common metabolic disorders requires a simple test with a low false-positive rate. Using nocturnal salivary cortisol (NSC), which we first validated in patients with suspected and proven Cushing's syndrome, we screened 106 overweight patients with type 2 diabetes mellitus, a group at high risk of SCS and nontumoral hypothalamic-pituitary-adrenal axis perturbations. Our hypothesis was that a lower false-positive rate with NSC was likely, compared with that reported with the dexamethasone suppression test (DST) (10–20%), currently the foundation of diagnosis of SCS. No participant had clinically apparent Cushing's syndrome. Three participants had an elevated NSC but further testing excluded SCS. In this study, NSC had a lower false-positive rate (3%) than previously reported for the DST. Given the reported excellent performance of NSC in detection of hypercortisolism, the low false-positive rate in SCS suggests NSC may be superior to the DST for SCS screening. The NSC and DST should be compared directly in metabolic disorder patients; although our data suggest the patient group will need to be substantially larger to definitively determine the optimal screening test.