Cortisol response to dexamethasone in women with premenstrual syndrome.

There were no significant differences in post-dexamethasone cortisol between the follicular and luteal phase of the menstrual cycle in both women with premenstrual syndrome (PMS) and control subjects tested on these two occasions. Within each menstrual cycle phase, there were also no differences in post-dexamethasone cortisol between the two groups. In a second group of control subjects tested on a single occasion, post-dexamethasone cortisol values were higher when subjects were tested in the middle 2 weeks of the menstrual cycle compared with the first and last weeks of the cycle. This phenomenon, possibly due to estrogen effects, suggests that post-dexamethasone cortisol should be assessed weekly in women with PMS to determine whether they also manifest this normally observed menstrual cycle phase-related pattern, or whether it is absent, reflecting a reproductive endocrine abnormality in this patient group.