[Doses-related effects of lynestrenol on ovulation]

8 women aged 22-28 with normal ovulatory menstrual cycles volunteered to take different doses of Lynestrenol to determine its effects on Luteineizing Hormone (LH) secretion and on plasma progesterone levels. Blood samples were taken in the morning and plasma was immediately separated. Results showed that body temperature varied unpredictably during the cycle and therefore could not be considered a reliable parameter of ovulation. 0.35 mg of Lynestrenol administered daily was enough to suppress ovulation as evidenced by the absence of LH during midcycle. Although differences exists in individual reactions administration of Lynestrenol beyond 0.6 mg. daily always suppresses ovulation because of hypothalamo-pituitary inhibition while doses below 0.5mg. daily can bring about episodic peaks. It is still not clear how Lynestrenol influences gonadotropins especially LH while intermittent bleeding seems to be the only sure side effect.