Central precocious puberty: A single blood sample after gonadotropin-releasing hormone agonist administration in monitoring treatment

This study was designed to evaluate whether a single blood sample drawn aft er the home injection of a long-acting gonadotropin-releasing hormone (GnRH ) agonist (GnRHa) in patients treated for central precocious puberty (CPP) could be a more simple and inexpensive test with respect to the conventiona l GnRH stimulating test in assessing adequate suppression of the pituitary- gonadal axis. The response to the first therapeutic injection of the GnRHa triptorelin was studied in 14 newly diagnosed untreated females with CPP. T he results were compared with the response that the same patients had to th e conventional GnRH stimulation test performed at the time of diagnosis. A significant increase in LH, FSH and E-2 levels was observed 12 h after the triptorelin intramuscular injection; serum peak values of LH (70.3 +/- 58.5 IU/l), FSH (44.2 +/- 21.7 IU/l) and E-2 (489.7 +/- 263.9 pmol/l) were sign ificantly greater than those obtained with the conventional GnRH test (LH 3 1.4 +/- 21.7, p = 0.002; FSH 19.8 +/- 10.7, p = 0.001; E-2 83.3 +/- 25, p < 0.001). In particular, the E2 response, 12 h after triptorelin injection, was clearly consistent with gonadal activation compared to the modest E2 in crease in response to the GnRH test. Thereafter 22 girls who were already b eing treated with triptorelin for CPP were evaluated to see whether a singl e blood sample drawn 12 h after the therapeutic home injection of GnRHa cou ld be informative in assessing adequate suppression of the pituitary-gonada l axis. This response was also compared to the conventional GnRH stimulatio n test performed 2 days before the therapeutic triptorelin injection. In 7 girls with evidence of pubertal progression, the E-2 response following the GnRHa injection (136.3 +/- 44.4 pmol/l) was significantly higher with resp ect to the response after the GnRH stimulation test (73.0 +/- 0.0; p < 0.02 ) indicating an inadequate suppression of the pituitary-gonadal axis. The p resent data suggest that a single blood sample drawn 12 h after the therape utic home administration of triptorelin provides a simple, comfortable and inexpensive means of monitoring pituitary as well as gonadal function in gi rls treated for CPP.