[Irregular secretion of prolactin in infertile women with normoprolactinemic galactorrhea]

Abnormal frequency and pulse amplitud of prolactin secretion in micro and macroprolactinomas has been atributed to a dysfunctional tumoral lactotrope. Previous evidence suggests that non tumoral hyperprolactinemia is caused by a hypothalamic dysfunction. The regularity of prolactin secretion has not been studied with cuantitative methods in patients with normoprolactinemic galactorrhea (NPG) which could be considered an entity that precedes non tumoral and tumoral hyperprolactinemia.

To analyze the 24-hour prolactin secretion pattern and its secretion regularity in a group of infertile women with normoprolactinemic galatorea.

A transversal-comparative study was carried out in 6 infertile women with normoprolactinemic galactorrhea and 4 healthy women as controls. The 24 hour prolactin profile, the ratio night time mean concentration/daytime mean concentrattion (NM/DM ratio) and apparent entropy (Ap En, Ap En ratio) were compared in the two groups.

Blunting of the nyctohemeral rythm and nocturn hyperprolactinaemia occurred in patients with normoprolactinemic galactorrhea (NPG). NM/DM ratio was lower in patients with NPG than in controls (1.28 +/- 0.25 vs. 1.75 +/- 0.05; p= 0.01). Higher irregularity of prolactin secretion was found in patients with NPG (ApEn: 0.853 +/- 0.158 vs 0.608 +/- 0.171, p=0.04; Ap En ratio: 0.839 +/- 0.11 vs 0.661 +/- 0.14; p=0.04).

The irregularity of prolactin secretion in patients with NPG is not dependant on the presence of a pituitary tumour which suggests that a hypothalamic dysfunction underlies this condition. An irregular secretion and a higher daily mass production of prolactin in patients with NPG could explain both galactorrhea and infertility.