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Dexamethasone Suppression Test, Low-Dose
|Test group||Dexamethasone Suppression Test|
|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|