There is still no consensus on simple methods to monitor the effectiveness of gonadotropin-releasing hormone analogs in girls with precocious or early puberty.

To evaluate the value of urinary luteinizing hormone (LH) and follicle-stimulating hormone (FSH) before and after triptorelin stimulation test detected by immunochemiluminometric assay (ICMA) to monitor the efficacy of triptorelin depot in girls with precocious or early puberty.

A total of 128 girls with precocious or early puberty were included, of whom 81 received triptorelin depot treatment (3.75 mg). Triptorelin (100 μg) stimulation tests were performed before and after 3 months treatment. The time of triptorelin stimulation test was designated as 0 h. Timed 12 h urine with recorded urine volume was collected before and after the test, defined as diurnal spontaneous (-24 h to -12 h), nocturnal spontaneous (-12 h to 0 h), diurnal stimulated (0 h to 12 h), and nocturnal stimulated urine (12 h to 24 h), respectively. LH and FSH were assayed by ICMA.

After 3 months of treatment, 67 girls completed sample collections, with 2 out of 67 girls experiencing inadequate efficacy. Serum and urinary gonadotropin levels decreased significantly after 3 months of treatment. The area under curve (AUC) of nocturnal spontaneous, diurnal stimulated, and nocturnal stimulated urinary FSH (UFSH) concentrations in determining efficacy were 0.962, 0.985, and 0.954. The three AUCs were all greater than serum peak LH (PLH, 0.746) or peak FSH (PFSH, 0.931). When nocturnal spontaneous, diurnal stimulated, and nocturnal stimulated UFSH concentrations were ≤ 5.24 IU/L, 6.94 IU/L, and 5.78 IU/L, the sensitivity was 93.8 %, 96.9 % and 95.4 %, and the specificity was all 100.0 %.

UFSH measured by ICMA from diurnal and nocturnal stimulated 12-hour urine samples can be used to assess the effectiveness of triptorelin depot in girls with precocious or early puberty. For a non-invasive and cost-effective option, spontaneous nocturnal urine may also be a suitable choice.