Endocrine Unit, Evgenidion Hospital, University of Athens Medical School, Athens, Greece
Increasing evidence derived from experimental and clinical studies
suggests that the hypothalamic-pituitary-thyroid axis (HPT)
and the hypothalamic-pitutitary-ovarian axis (HPO) are physiologically
related and act together as a unified system in a number of
pathological conditions. The suggestion that specific thyroid
hormone receptors at the ovarian level might regulate reproductive
function, as well as the suggested influence of estrogens at
the higher levels of the HPT axis, seems to integrate the reciprocal
relationship of these two major endocrine axes. Both hyper-
and hypothyroidism may result in menstrual disturbances. In
hyperthyroidism the most common manifestation is simple oligomenorrhea.
Anovulatory cycles are very common. Increased bleeding may also
occur, but it is rare. Hypothyroidism in girls can cause alterations
in the pubertal process; this is usually a delay, but occasionally
it can result in pseudoprecocious puberty. In mature women hypothyroidism
usually is associated with abnormal menstrual cycles characterized
mainly by polymenorrhea, especially anovulatory cycles, and
an increase in fetal wastage.
