Simple laboratory test of neuroendocrine disturbance in depression: 11 p.m. saliva cortisol

Saliva cortisol was measured at 11 p.m. in a sample of 74 psychiatric inpatients composed of 24 primary endogenous depressives, 40 secondary depressives and 20 nondepressives (DSM III and Saint-Louis criteria). Primary depressives had significantly higher 11 p.m. saliva cortisol levels than nondepressives (p less than 0.02) and secondary depressives (p less than 0.05). In contrast, there were no significant differences between secondary depressive and nondepressive saliva cortisol levels. A saliva cortisol cutoff limit of 3.45 nmol/l identified primary depressives with a sensitivity of 62.5% and with a specificity of 75% in the depressive group, and 90% in the nondepressive group. The measurement of saliva cortisol at 11 p.m. could be used alone as a reliable and practical index of hypothalamic-pituitary-adrenal axis activity in depression, especially in outpatients.