ESPE Abstracts

Background: The gold standard for adequate hormonal suppression during GnRHa treatment for precocious puberty (PP) is attenuated serum LH levels in response to LHRH stimulation.

Objective and hypotheses: We aimed to compare basal and post-GnRHa levels of LH to LHRH stimulation test, and to evaluate first-voided urinary LH (ULH) as a non-invasive alternative method for monitoring treatment.

Method: Seventeen girls with PP were followed over 12–36 months during GnRHa (Decapeptyl) treatment. ULH and serum LH levels were obtained every 4 months before and 24 h after GnRHa administration respectively, along with clinical evaluation of pubertal staging, growth velocity (GV) and bone age (BA) advancement. LHRH stimulation test was performed annually. ULH cutoff was 1.62 IU/l based on 2 S.D. above the mean in 29 pre-pubertal girls.

Results: A total of 36 LHRH stimulation tests demonstrated adequate suppression of gonadotropins with peak LH of 0.57±0.33 (0.1–1.4 IU/l). Corresponding mean post-GnRHa LH levels was 0.59±0.33 (0.1–1.6) and mean basal LH levels was 0.27±0.16 (0.1–0.7 IU/l). Both tests were correlated with LHRH-stimulated LH: R=0.807 and R=0.696 respectively (P<0.001). Corresponding mean ULH levels was 1.12±0.38 IU/l. Among 90 pair-tests of ULH and post-GnRHa LH measurements obtained over 380 patient-months, six ULH measurements levels were above the pre-pubertal cutoff (range 1.66–2.21) but none of post-GnRHa LH levels. In spite of adequate hormonal suppression, 21 episodes of clinical breakthrough were recorded: 13 episodes of GV-SDS >2 and 11 episodes of BA advancement. ULH and post GnRH LH levels measured during these episodes were similar to levels obtained during clinical suppression.

Conclusion: Decapeptyl Depot treatment provides adequate suppression of the hypothalamic – pituitary – gonadal axis during PP. When in doubt, both pre-GnRHa and post-GnRHa LH levels can provide reliable data on hormonal suppression. Clinical breakthroughs during treatment do not reflect unsuppressed gonadotropins and therefore therapy intensification is not necessarily indicated.