To the Editor.—
In the article by Stokes et al1 about a multicenter study of the 1-mg dexamethasone suppression test (DST), the authors reported a very high percentage of abnormal test results in healthy subjects (35%, when three post-DST blood samples were used) and no close linkage between DST nonsuppression and cortisol hypersecretion (measured by urinary free cortisol excretion every 24 hours). Previous studies with 2 mg of dexamethasone, however, revealed a much lower rate of DST nonsuppression in healthy subjects2 and found an abnormality of 2 mg of DST to be a highly specific, although not very sensitive, indicator for hypercortisolism.3 Taken together, these results suggest that a dose of 1 mg of dexamethasone is too low to provide reliable DST results. We have recently performed 160 1-mg DSTs in 93 psychiatric inpatients who had different psychiatric diagnoses.4 The post-DST plasma cortisol level was measured at 9 AM,
Berger M, Pirke K, Krieg J, von Zerssen D. Limited Utility of the 1-mg Dexamethasone Suppression Test as a Measure of Hypercortisolism. Arch Gen Psychiatry. 1985;42(2):201–202. doi:10.1001/archpsyc.1985.01790250095013
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