Postdexamethasone prolactin and cortisol: a biological state variable in depression.

In 70 inpatients with major depressive disorder postdexamethasone cortisol and prolactin, but not baseline cortisol and prolactin, was found to correlate significantly with various state variables of depression. Postdexamethasone prolactin appeared to be a more specific state variable of depression compared with postdexamethasone cortisol. While prolactin was decreased following dexamethasone in controls and nonendogenous depressed patients, in endogenous depressed patients prolactin was increased by 30%. Due to this inverse prolactin response to dexamethasone, the sensitivity of this test should be considerably increased by using a higher dexamethasone dosage. The DST failed to be a diagnostic marker for any subgroup of depression.