Abstract
LH pulses are detectable in some prepubertal children but accurate determination of pulse frequency has been limited by the sensitivity of the LH RIA, the low pituitary responsiveness to GnRH and the relatively short periods of sampling. 8 males aged 12.0 to 19.8 years with delayed puberty and/or growth delay were studied to determine whether pituitary responsiveness can be amplified, and endogenous LH/GnRH pulse frequency accurately assessed, by short term low dose (0.1 ug/Kg) pulsatile GnRH priming. GnRH was administered subcutaneously every 2 hours between 23.00 and 09.00h for 7 days by portable minipumps. Before and after the 7-day treatment, blood samples were obtained at 10 minute intervals for 8-12 hours between 20.00-08.00h for RIA measurement of gonadotrophins and T followed by I/V GnRH (0.25 ug/kg) test.
In 4 patients with a significant pre-treatment nocturnal LH rise, pulsatile GnRH stimulation did not signficantly increase endogenous LH pulse frequency or amplitude. In 4 subjects with probable Kallmann's syndrome or idiopathic hypogonadotrophic hypogonadism, responses to I/V GnRH increased dramatically (LH 5.6 ± 0.5 fold, FSH 6.5 ± 2.3 fold). In 2 of them no LH pulses were observed before or after GnRH priming and only FSH pulses (4/12h and 1/12h) post-stimulation. In the other 2, LH pulses increased from zero to 7/12h and 3 to 6/8h respectively.
These data show that nocturnal pulsatile GnRH priming can augment pituitary responsiveness and increase the number of detectable gonadotrophin secretory episodes only in prepubertal patients without pre-existing nocturnal LH elevation. Increasing GnRH pulse amplitude may be a major mechanism in pubertal initiation. Short term pulsatile GnRH priming may be useful in distinguishing permanent hypogonadotrophic hypogonadism from constitutionally delayed puberty.
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Butler, G., Wu, F. & Kelnar, C. EFFECTS OF SHORT TERM PULSATILE GnRH STIMULATION ON SPONTANEOUS EPISODIC LH/GnRH SECRETION IN PREPUBERTAL AND HYPOGONADOTROPHIC MALES. Pediatr Res 20, 1197 (1986). https://doi.org/10.1203/00006450-198611000-00142
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DOI: https://doi.org/10.1203/00006450-198611000-00142