In addition to its ability to decrease plasma cortisol levels,
dexamethasone can also significantly decrease plasma prolactin levels. In
52 psychiatric patients, including 26 patients with primary major
depression or schizoaffective depression, primarily affective type, there
was a significant association between nonsuppression of plasma cortisol and
prolactin after administration of dexamethasone. These results suggest that
the abnormal cortisol response to dexamethasone in some psychiatric
patients may be due to a pituitary gland abnormality rather than to a
limbic system abnormality. The sensitivity and specificity of the
dexamethasone suppression test for endogenous depression were less than
previously reported.Abstract Teaser