UCSF Navigation Bar

UCSF Departments of Pathology & Laboratory Medicine Home Page

Lab Manual for Moffitt-Long and Mount Zion

Lab Manual for SFGH

Internal Resources

Click here for more information about laboratory operations and procedures

Dexamethasone Suppression Test, Low-Dose

Item Value
Approval req'd? No
Available Stat? No
Test code
Test group Dexamethasone Suppression Test
Container type
Sample type see Cortisol
Normal range See Additional Information
Additional information For Diagnosis of Cushing's Syndrome.

Rapid Test (based on Pavlatos FC et al. JAMA 1965;193:720): Obtain a baseline serum cortisol at 0700-0800 hours. Administer 1.0 mg po dexamethasone that evening at 2300 hours and obtain another serum cortisol at 0700-0800 hours the following morning. Interpretation: A normal response (suppressibility) is a reduction of the post-dexamethasone serum cortisol to < 5 µg/dL (< 140 nmol/L).

Standard Test (based on Liddle GW. J Clin Endocrinol Metab 1960;20:1539): Obtain a baseline serum cortisol at 0700-0800 hours and a 24 hour urine collection of urine for 17-OH corticosteroids beginning at the same time. On the following day administer 0.5 mg po dexamethasone q6h for 8 doses. Repeat the 24 hour urine 17-OHC collection during day 2 of dexamethasone administration and repeat the plasma cortisol at 0700-0800 hours on the morning after the last steroid dose.

Interpretation: A normal response (suppressibility) is a reduction in cortisol to < 5 µg/dL (< 140 nmol/L) and of 17-OHC to < 4 mg/d (< 11 µmol/d).

Significance: An (abnormal) lack of suppression typifies Cushing's Syndrome.
Last Updated 10/15/2008 9:49:54 AM
Entry Number 299

If you have additional questions regarding this test, please call: 415-353-1667

Search Our Test Menu
UCSF home page UCSF home page About UCSF Search UCSF UCSF Medical Center