The Utility of the High Dose Dexamethasone Suppression Test in Confirming the Diagnosis of Cushing's Disease
Endocrine Practice, 09/09/2011
Clinical Article
Aytug S et al. – The study conclude that the overnight 8–mg high dose dexamethasone suppression (HDDS) test accurately confirmed the diagnosis of Cushing's disease with a high sensitivity of 95% with a criterion of > 50% suppression; the sensitivity was only 62% using a more precise cutoff of > 80% suppression. The 2–day HDDS with a criterion of > 90% suppression of 24–hour urine free cortisol (UFC) had a sensitivity of 64%. These results confirm the limited precision of the HDDS tests.
Methods- In this retrospective study, the authors reviewed medical records of patients who underwent either the overnight 8–mg HDDS test or a 2–day 2–mg HDDS every six hours.
- Percent suppression of a.m. serum cortisol or percent suppression of 24–hour urine free cortisol (UFC) were calculated.
- One hundred and forty one patients with proven Cushing's disease underwent a HDDS test.
- Seventy–seven (55%) underwent the overnight 8–mg HDDS test and 64 (45%) underwent a 2–day 2–mg HDDS every six hours.
- With the overnight 8–mg test, 73 of 77 (95%) had > 50% and 48 of 77 (62%) had > 80% suppression of the morning serum cortisol.
- With the 2–day 2–mg HDDS test, only 41 of 64 (64%) had > 90% suppression of 24–hour UFC.
