Hyperprolactinaemia and luteal insufficiency.

Prolactin interferes with the function of the corpus luteum, as was demonstrated by repeatedly finding a short luteal phase in the ovulatory cycles of two hyperprolactinaemic women after prolactin supression by bromocriptine had been discontinued. In hyperprolactinaemic ovulatory cycles excretion of pregnanediol in urine was less and plasma-progesterone concentrations were lower than in normo-prolactinaemic cycles. When the amenorrhoea-galactorrhoea syndrome recurred the symptoms appeared in the following order: (1) serum-prolactin increased and the luteal phase became shorter; (2) galactorrhoea appeared; (3) ovulation was missed; (4) menstruation was missed. All these abnormalities may be treated by prolactin suppression, but the effect of treatment does not persist for long after bromocriptine administration ceases.