A SINGLE-SAMPLE, SUBCUTANEOUS GONADOTROPIN-RELEASING-HORMONE TEST FORCENTRAL PRECOCIOUS PUBERTY

Objective. We compared a rapid,subcutaneous (SQ), single-sample gonado tropin-releasing hormone (GnRH) stimulation test with the standard mul tiple-sample, intravenous (IV) GnRH stimulation test used in the evalu ation of central precocious puberty (CPP). Methods. We evaluated 22 pa tients presenting with evidence of precocious puberty, GnRH (100 mu g) was administered subcutaneously in the clinic setting with single ser um luteinizing hormone (LH) measured 40 minutes after injection. A sta ndard IV GnRH stimulation test was performed within 2 weeks, with seru m LH obtained at 0, 20, 40, and 60 minutes. LH was assayed by immunoch emiluminometric assay. Results. The mean peak LH levels after IV and S Q testing were identical. A significant correlation (r = .88) was foun d between the LH determined by SQ stimulation and the peak LH determin ed by IV GnRH testing. CPP was diagnosed (LH, greater than or equal to 8 IU/L) by both SQ and IV testing in 7 of 22 patients and was exclude d by both tests in 14 of 22 patients. A diagnostic discrepancy between peak IV and SQ results was seen in 1 patient. Conclusions. We conclud e that mean GnRH-stimulated LH levels from rapid SQ and standard IV te sting are indistinguishable and that individual LH levels by each meth od are strongly correlated. A rapid SQ GnRH test is a valid tool for l aboratory confirmation of CPP.