Drug intake and the dexamethasone suppression test.

The dexamethasone suppression test (DST) is being used clinically as a diagnostic laboratory test for depression. Drug histories collected from 336 psychiatric inpatients revealed that 60% were taking one or more drugs suspected of altering DST results in either a false-positive or false-negative manner. Practical limitations of the DST as a biologic marker of affective syndromes in relation to patient drug use are discussed.