The citalopram challenge test (CCT) is a new neuroendocrinological test which shows serotoner- gic activity via prolactin and cortisol plasma levels. Advantages of the CCT comparing to the fenfluramine challenge test are: parenteral i.v. - administration - high citalopram selectivity and safety. The aim of the study was to elaborate the methodology of CCT, to gather groups of 1) depressive patients, 2) anxious patients and 3) healthy volunteers; and to check the hypothesis about flattening of the hormonal peak in the group of depressive patients and excessive hormonal peak in the group of anxious patients, and the hypothesis about the normalization of such modifi- ed responses after antidepressant treatment. The methodology of CCT, observed parameters, obtained data and results are presented: final statistical processing of 3 groups (n = 3x10) shows a constant serotonin response 30-40 minutes after rapid citalopram infusion. PRL response was significantly flattened in the group of depressive patients (p < 0.05). There was no significant finding of excessive response in the group of anxiety disorders. Basal plasma levels of PRL of anxious patients were higher than the levels of the control group (p < 0.05). Criteria of positivity of CCT for depression are suggested: prolactin level after citalopram infusion not higher than 125% of the basal level. Other statistical issues are analyzed. The CCT could be a marker of depressive disorders after a more extensive validization.

        Key words: citalopram, challenge test, depression, anxiety disorder, prolactin, cortisol.