Assessment of the utility of the high-dose dexamethasone suppression test in confirming the diagnosis of Cushing disease

Endocr Pract. Mar-Apr 2012;18(2):152-7. doi: 10.4158/EP11179.OR.

Abstract

Objective: To determine the utility of high-dose dexamethasone suppression (HDDS) tests to confirm the diagnosis of Cushing disease (CD).

Methods: In this retrospective study, we reviewed medical records of patients who underwent either the overnight 8-mg HDDS test or the 2-day 2-mg HDDS test every 6 hours. The percentage suppression of morning serum cortisol and the percentage suppression of 24-hour urine free cortisol (UFC) were calculated.

Results: Of 141 patients with proven CD who underwent HDDS tests, 77 (55%) underwent the overnight 8-mg HDDS test and 64 (45%) underwent the 2-day 2-mg HDDS test every 6 hours. With the overnight 8-mg HDDS test, 73 of 77 patients (95%) had greater than 50% suppression and 48 of 77 patients (62%) had greater than 80% suppression of the morning serum cortisol in comparison with the baseline value. With the 2-day 2-mg HDDS test, only 41 of 64 patients (64%) had greater than 90% suppression of 24-hour UFC.

Conclusion: We conclude that the overnight 8-mg HDDS test accurately confirmed the diagnosis of CD with a high sensitivity of 95% with use of a criterion of greater than 50% suppression; in contrast, the sensitivity was only 62% with use of a more precise cutoff of greater than 80% suppression. The 2-day 2-mg HDDS test with a criterion of greater than 90% suppression of 24-hour UFC had a sensitivity of 64%. These results confirm the limited precision of the HDDS tests.

Publication types

  • Evaluation Study

MeSH terms

  • Adrenal Cortex / drug effects
  • Adrenal Cortex / metabolism
  • Adrenal Cortex / physiopathology
  • Adult
  • Cohort Studies
  • Dexamethasone* / administration & dosage
  • Dose-Response Relationship, Drug
  • Female
  • Follow-Up Studies
  • Glucocorticoids* / administration & dosage
  • Humans
  • Hydrocortisone / blood
  • Hydrocortisone / metabolism
  • Hydrocortisone / urine
  • Male
  • Medical Records
  • Middle Aged
  • Pituitary ACTH Hypersecretion / blood
  • Pituitary ACTH Hypersecretion / diagnosis*
  • Pituitary ACTH Hypersecretion / physiopathology
  • Pituitary ACTH Hypersecretion / urine
  • Retrospective Studies
  • Sensitivity and Specificity
  • Time Factors

Substances

  • Glucocorticoids
  • Dexamethasone
  • Hydrocortisone