Effect of mestranol and chlormadinone acetate on urinary excretion of FSH and LH

Urinary excretion of FSH and LH was studied in normal ovulating women during 27 control cycles and during 37 cycles when various doses of mestranol and/or chlormadinone acetate were given singly, sequentially, or in combination. During the first cycle of treatment, the major effect of mestranol was a suppression of FSH excretion, with the effect diminishing as dosage levels were decreased from 100 to 80 to 60 μg per day. The effect on LH was definite but less consistent. Commencement of therapy on cycle day 1 was more suppressive than commencement on day 5. Repeated cyclic administration of mestranol suppressed both FSH and LH excretion. However, sporadic detectable levels of LH were seen occasionally even after 12 cycles of treatment. A dose of 10 μg mestranol per day had a stimulatory rather than a suppressive action on the excretion of both FSH and LH. Chlormadinone acetate at 2 mg. per day affected both FSH and LH excretion in rather unpredictable fashion. Simultaneous administration of chlormadinone acetate and mestranol appeared to have an additive effect.