The dexamethasone suppression test applied to inpatients of a Brazilian psychiatric hospital.

1. The dexamethasone suppression test (DST) was applied to three groups of Brazilian psychiatric inpatients as follows: 93 patients were tested both on admission and at discharge; 166 patients were tested only on admission, and 43 patients only at discharge. All patients were examined physically and diagnosed using the Research Diagnostic Criteria (RDC) and a history of drug use and weight loss one week before admission was obtained. 2. On admission, a suppression rate of 41% (106 positive tests for 259 patients) was obtained with the DST regardless of diagnostic group, whereas at discharge the rate was 27%. 3. The rate of nonsuppressors in each diagnostic group on admission was highest among the endogenous major depressive patients (55%), followed by patients with drug-use disorders (48%), organic disorders (44%), and alcoholic patients (40%). 4. Since weight loss, unsupervised drug therapies and several organic pathologies, all of which are common events in Third World countries like Brazil, may lead to false DST positive results, 46% of the 106 nonsuppressors could be considered to be false positives. The rate of false positives would reach 74% if only the 23 primary endogenous major depressive nonsuppressor patients were considered. Weight loss was the most common cause of nonsuppression responses. 5. In view of the poor living conditions of the population, the apparent deficiencies of the Public Health Care System and the widespread, largely uncontrolled use of medications, it is suggested that the DST should be used cautiously, if ever, in Brazil and probably in other Third World countries.