Characteristics of urinary luteinizing hormone (LH) during the induction of LH surges of different magnitude in blood

Urinary luteinizing hormone (LH) testing has been proposed asa reliable method for the prediction of ovulation but its accuracyhas been challenged by some studies. To check how accuratelythe oscillations of urinary LH reflected the plasma changes,surges of LH of different magnitude and duration were artificiallyinduced in plasma and the hormone was measured simultaneouslyin urine. Post-menopausal women (n = 16) were stimulated during1 week with a combination of transdermal oestradiol (400 µg)and i.m. progesterone (25 mg on day 4, 50 mg on day 5) to obtainan LH discharge comparable with the pre-ovulatory LH peak. Ashort and moderate peak of LH was induced by the i.v. injectionof 100 µg gonadotrophin-releasing hormone (GnRH) in sixpre-menopausal women, whereas an LH discharge of higher amplitudeand longer duration was induced by a single dose of 0.3 mg s.c.buserelin. The total urine production of the day was fractionatedinto 8 h periods. LH was measured by a commercial radioimmunoassay.Unambiguous peaks of LH were detected in the urine of all thewomen stimulated with either oestradiol plus progesterone orbuserelin, but in only three out of the six women receivingGnRH. The urine LH reproduced the plasma changes of the hormonewith short delay since the peaks were mostly detected in thesame time fraction in which the serum discharge occurred.