Age, medical illness, and the DST in depressed general hospital inpatients.

A dexamethasone suppression test (DST) was administered to 89 general hospital inpatients as part of an evaluation of depressed mood. Among the 55 patients with major depressive disorder (MDD), age was positively correlated with postdexamethasone cortisol (r=.317, p=.002 at 4 p.m.). The patients without MDD did not show this effect. Postdexamethasone cortisol concentrations of 15 micrograms/dl or greater were seen in 31% of 32 patients over 60 with MDD; they did not occur in 23 patients under 60 with MDD. The results suggest a clinically relevant effect of age on the DST in patients with MDD.