Faculty Collaboration Database

The low-dose dexamethasone suppression test: a reevaluation in patients with Cushing's syndrome. J Clin Endocrinol Metab 2004 Mar;89(3):1222-6

Date

03/06/2004

Pubmed ID

15001614

DOI

10.1210/jc.2003-030207

Scopus ID

2-s2.0-1642277979   127 Citations

Abstract

Low-dose dexamethasone suppression testing has been recommended for biochemical screening when Cushing's syndrome is suspected. The criterion for normal suppression of cortisol after dexamethasone is controversial. To assess diagnostic utility (sensitivity), we report the results of low-dose dexamethasone suppression testing in 103 patients with spontaneous Cushing's syndrome. There were 80 patients with Cushing's disease (78%), 13 with the ectopic ACTH syndrome (13%), and 10 with cortisol-producing adrenocortical adenomas (10%). Fourteen (18%) of 80 patients with Cushing's disease suppressed serum cortisol to less than 5 micro g/dl (<135 nmol/liter) after the overnight 1-mg test, whereas six patients (8%) actually showed suppression of serum cortisol to less than 2 micro g/dl (<54 nmol/liter). In addition, the 2-d, low-dose dexamethasone suppression test yielded false-negative results in 38% of patients when urine cortisol was used and 28% when urinary 17-hydroxycorticosteroids were used. Serum cortisol after the 1-mg test correlated with baseline urinary free cortisol (r = 0.705, P < 0.001), plasma ACTH level (r = 0.322, P = 0.001), and urinary free cortisol after the 2-d test (r = 0.709, P = 0.001). This study provides evidence that low-dose dexamethasone may suppress either plasma cortisol or urinary steroids to levels previously thought to exclude Cushing's syndrome and that these tests should not be used as the sole criterion to exclude the diagnosis of endogenous hypercortisolism.

Author List

Findling JW, Raff H, Aron DC

Authors

James W. Findling MD Staff Physician in the Multi-Specialty department at Medical College of Wisconsin
Hershel Raff PhD Professor in the Medicine department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

17-Hydroxycorticosteroids
Adult
Aged
Cushing Syndrome
Dexamethasone
Glucocorticoids
Humans
Hydrocortisone
Mass Screening
Sensitivity and Specificity