A single sample GnRHa stimulation test in the diagnosis of precocious puberty

CONTEXT Gonadotropin-releasing hormone (GnRH) has been the standard test for diagnosing central precocious puberty. Because GnRH is no longer available, GnRH analogues (GnRHa) are now used. Random LH concentration, measured by the third-generation immunochemiluminometric assay, is a useful screening tool for central precocious puberty. However, GnRHa stimulation test should be considered, when a basal LH measurement is inconclusive. However optimal sampling times for luteinizing hormone (LH) have yet to be established. PURPOSE To determine the appropriate sampling time for LH post leuprolide challenge. METHODS A retrospective analysis of multi-sample GnRHa stimulation tests performed in 155 children (aged 1-9 years) referred for precocious puberty to Texas Children's Hospital.After 20 mcg/kg of SQ leuprolide acetate, samples were obtained at 0, 1, 3, and 6 hours. RESULTS Of 71 children with clinical evidence of central precocious puberty, fifty nine children had a peak LH >5 mIU/mL. 52 (88%) of these responders had positive responses at 1 hour (95% CI is 80-96%), whereas all 59 children (100%) had a peak LH response >5 mIU/mL at 3 hours (95% CI is 94-100%), P = 0.005. CONCLUSIONS A single serum LH sample collected 3 hours post GnRHa challenge is the optimal sample to establish the diagnosis of central precocious puberty.