Studies on the measurement and pharmacodynamics of human follicle-stimulating hormone

The levels of immunoreactive follicle-stimulating hormone (FSH), luteinizing hormone (LH), prolactin (PRL), cortisol, and estradiol (E2) have been determined in serial samples of peripheral plasma from four subjects during the continuous, subcutaneous administration of Buserelin (Hoechst [UK] Ltd., Hounslow, UK) (250 micrograms/day) and after the intramuscular injection of purified, urinary FSH (Metrodin, Serono Laboratories [UK] Ltd., Welwyn Garden City, UK) (150 IU). During Buserelin administration the geometric mean levels of FSH and LH as measured by immunoradiometric assay were reduced by 87% and 37%, respectively, when compared with the corresponding values for days 1 and 2 of the menstrual cycle. After the intramuscular injection of FSH, peak levels (from 3.4 to 6.2 IU/l) occurred in peripheral plasma between 6 and 18 hours later. The levels were significantly elevated after 72 hours (P less than 0.01, Student's paired t-test). There was no obvious effect of the drugs on the circadian rhythms of plasma PRL or cortisol, and no significant effect on the circulatory levels of LH or E2.