Periods that are too frequent (more often than every 26 days, “metrorrhagia”) can be related to several predisposing factors:

• If the periods are otherwise normal, then a short “luteal phase” or insufficient ovarian production of progesterone may be responsible.
• If the periods are inconsistent, then failure to ovulate and the resulting anovulatory bleeding may be responsible.
• If the periods are actually normal and once a month, but there are episodes of bleeding in between the periods, then mechanical factors such as fibroids or polyps may be responsible.

Women with hyperthyroidism are classically described as experiencing frequent, heavy periods. They, in reality, rarely show that pattern, but we usually screen these patients for thyroid disease anyway.