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

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.

• Authors: Serhat Aytug, Edward R Laws Jr, Mary Lee Vance
• Journal: Endocrine practice : official journal of the American College of Endocrinology and the American Association of Clinical Endocrinologists (Endocr Pract) 2012 Mar-Apr Vol. 18 Issue 2 Pg. 152-7 ISSN: 1934-2403 [Electronic] United States
• PMID: 21856594 (Publication Type: Evaluation Study, Journal Article)

Chemical References

• Glucocorticoids
• Dexamethasone
• Hydrocortisone

Topics

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