INFLUENCE OF LOW DOSE OESTROGEN ON CIRCULATING PROLACTIN, LH AND FSH LEVELS IN POST-MENOPAUSAL WOMEN

Abstract

The effect on serum prolactin, LH [luteinizing hormone] and FSH [follicle-stimulating hormone] levels of 25 .mu.g ethinylestradiol administered daily per os during 27 consecutive days was investigated in 5 post-menopausal women aged 52-78. Blood samples were collected before, during and after treatment. The hormones were assayed in serum by radioimmunological methods. LH and FSH decreased progressively and significantly from 120 and 115 mlU/ml before treatment to 52 and 51 mIU/ml, respectively after 3 wk of estrogen administration. Two wk after interruption of treatment, LH (90 mIU/ml) and FSH (112 mIU/ml) were significantly higher than during the last week of treatment. Mean prolactin level increased from 127 .mu.U[.mu. units]/ml before treatment to 237 .mu.U/ml after 10 days of estrogen administration (P < 0.001). This increase was significant after 4-8 days, and the levels remained about twice as high as the control values for the rest of the treatment period. Two weeks after interruption of treatment, serum prolactin had fallen (136 .mu.U/ml) to the pre-treatment levels. Such results raise the question of possible effects of elevated levels of this hormone during long term estrogen medication in post-menopausal women on the development of breast cancer.