The Dynamic Trends of Urinary LH and FSH Assayed by ICMA During Triptorelin Stimulation Tests in Girls - a Pilot Study.

BACKGROUND: Gonadotropin-releasing hormone stimulation test is a gold standard for evaluating the function of the hypothalamic-pituitary-gonadal axis (HPGA) in children. These tests are usually uncomfortable because of multi-venipunctures. A urine specimen is a good alternative because it is noninvasive and convenient. More studies have shown the correlation between sera and urine LH and FSH levels under different physiological and pathological conditions. METHODS: The study investigated the dynamic trends of urine LH (uLH) and FSH (uFSH) assayed by immunochemiluminometric assays (ICMA) during triptorelin stimulation tests in girls. The triptorelin stimulation tests were performed in 52 girls with disorders of puberty. The time 0 hour was regarded as the start time of the test (8:30 am). The day before the tests, urine samples were collected at 12 hours diurnal (-24 hours ~ -12 hours) and nocturnal (-12 hours ~ 0 hour) time points. On the day of the testing, the first 12 hours (0 hour ~ 12 hours), the second 12 hours (12 hours ~ 24 hours), the third 12 hours (24 hours ~ 36 hours), the fourth 12 hours (36 hours ~ 48 hours), the third and fourth overnight urine samples were also collected. The LH and FSH levels were assayed by ICMA, and uLH and uFSH were corrected for creatinine (Cr). RESULTS: The HPGA in 41 girls was activated but it was nonactivated in 11 girls. In girls with HPGA activated, uLH/Cr or uFSH/Cr was significantly elevated within 24 hours, and gradually dropped to baseline after 48 hours. When HPGA was nonactivated in girls, there were the same dynamic trends but much lower amplitude of uLH/Cr or uFSH/Cr, which dropped to baseline after 24 hours. CONCLUSIONS: The stimulated uLH and uFSH assayed by ICMA are valuable for evaluating the function of HPGA in girls, and the valuable time window is within 24 hours.