ESPE Abstracts

Introduction: Comprehensive evaluation of the gonadotropic axis, including pituitary and gonadal assessment, using a diagnostic test with aGnRH (Triptorelin) could be useful in the differential diagnosis between hypogonadotropic hypogonadism (HH) and self-limited delayed puberty (SLDP) or amenorrhea of unknown cause.

Objective: To assess the performance of the Triptorelin test for the diagnosis of HH and to compare it with the GnRH infusion test.

Methods: We conducted a case-control study nested in a prospective cohort of male patients with suspected HH or SLDP and female patients with suspected HH or amenorrhea of unknown cause. Following a random order, all patients underwent the Triptorelin test [0.1 mg SC injection and blood sampling at 3 and 24 hours for determination of serum LH, FSH and Estradiol (E₂) in girls and LH, FSH and Testosterone (T) in boys], and the standard 120-minute GnRH infusion test [0.1 mg IV infusion during 2 h and blood sampling for LH and FSH measurement at 15, 30, 45, 60 and 120 minutes] in addition to long-term clinical follow-up. FSH, LH, E₂ and T were measured by ECLIA, Cobas e411, Roche.

Results: 20 patients were included: 10 males [median age (range): 15.9 yrs (13.5-17.9)] and 10 females [15.0 yrs (17.2-20)]. After sufficient follow-up, HH was diagnosed in 14 patients (7 males and 7 females), while 3 males presented SLDP and 3 females recovered menstrual cycles. LH-3h and FSH-3h in the Triptorelin test had a high correlation with LH and FSH maximum values in the GnRH infusion test (r =0.95, 95%CI: 0.85-0.98 for both correlations). FSH-3h <10.6 IU/mL and E₂-24h <50 pg/mL confirmed HH diagnosis in girls, while in boys LH-3h <15 IU/L and T-24h < 10 ng/dL made the diagnosis of HH in boys.

Conclusion: aGnRH stimulation with Triptorelin 0.1 mg SC seems to be a simple and effective test to evaluate the overall dynamics of the gonadotropic axis response (including gonadal steroidogenesis) in patients suspected of having HH. The combination of LH-3h with T-24h in boys and FSH-3h with E₂-24h in girls may be useful to make the differential diagnosis between HH and SLDP or amenorrhea of unknown cause, respectively, with a diagnostic outcome similar to that of the more invasive GnRH infusion test, thus reducing patient discomfort. These preliminary results need to be validated in a larger cohort to further calculate the appropriate cut-off values and their diagnostic accuracy.