Dexamethasone suppression test (DST) and thyrotropin releasing hormone (TRH) stimulation test were performed in 34 patients with endogenous depression. Compared with 33 psychiatric controls (limit of discrimination for serum cortisol of 275 nmol/l = 10 micrograms/100 ml) the specificity of the DST was 91% and the sensitivity was 65%. Compared with 24 healthy subjects the sensitivity of the TRH test was 24%, and the combined sensitivity for the DST and the TRH test was 76%. In contrast to the TRH test the DST showed a significant relationship (r = 0.54, P less than 0.01) to the Hamilton Rating Score. Repeating the tests after clinical recovery parallel changes of the two tests were found in 14 of 19 patients with abnormal DST in the depressed phase. In the remaining five patients the DST normalized, while the TRH test remained unchanged. It is suggested that both the apparent higher diagnostic sensitivity and the higher rate of normalization after clinical recovery of the DST is due to the dependency of the severity of depression.

The dexamethasone suppression test (DST), the thyrotropin releasing hormone (TRH) test and the Newcastle II depression rating (NII) were compared with the clinical diagnosis and evaluated in 61 patients fulfilling the criteria of an affective disorder according to the DSM-III classification. A statistically significant correlation between clinical diagnosis and DST as well as NII, but not between clinical diagnosis and TRH test, was found. There was no correlation between DST and the severity of depression according to the Hamilton depression rating. The nosographic and the diagnostic specificities and sensitivities for the DST, TRH test and NII and DST and NII, a nosographic sensitivity of 50% and a nosographic specificity of 84% were found. Correspondingly, the diagnostic sensitivity was 43% and the diagnostic specificity was 88%. The DST and the TRH test were found of no value in the prediction of the response to antidepressive treatment. Mainly because of a low diagnostic sensitivity the NII, the DST and the TRH test are of limited value in the diagnosis of depressive disorders.

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