Thyroid axis function during the menstrual cycle in women with premenstrual syndrome.

Fifteen women with premenstrual syndrome (PMS) and 15 control women were tested twice for thyroid axis measures, once during the follicular and once during the luteal phase of the menstrual cycle. While PMS and control women did not differ in mean hormone values during either phase of the menstrual cycle, PMS women showed significantly greater variability in hormone measures including TSH, T3 uptake, T4, and FTI relative to controls. These findings are consistent with the conceptualization that, for a subset of women with PMS, thyroid axis abnormalities may contribute to their disorder. Additionally, when analyzed in the sample as a whole, the menstrual cycle exerted a significant effect on reverse T3 with greater levels observed in the luteal relative to the follicular phase of the cycle.