Diagnostic heterogeneity and the DST in consecutive psychiatric admissions.

There is uncertainty about the clinical usefulness of the dexamethasone suppression test (DST). It is also unclear whether there are advantages to a 1-mg or 2-mg DST. Eighty-three consecutive psychiatric inpatients were randomly given a 1-mg or 2-mg DST within the first week of admission. Sensitivity, specificity, and diagnostic confidence are reported for this group, and also in combination with those for 119 semi-consecutive psychiatric admissions. Although rates of nonsuppression were consistently higher in patients with affective disorders than in patients with other diagnoses, the diagnostic confidence of the DST for major depression in a diverse and unselected patient population was not greater than the prevalence of the disorder. The DST does not appear to be useful for clinical diagnostic decision-making. Nonetheless, the DST may still be an important biological marker in neuroendocrine psychiatric research.