Single random measurement of urinary gonadotropin concentration for screening and monitoring girls with central precocious puberty

PURPOSE: The gold standard for assessing pubertal activation is the gonadotropinreleasing hormone (GnRH) stimulation test (GnRHST), which is invasive, time-consuming, and inconvenient. This study evaluated whether a single random measurement of urinary luteinizing hormone (LH) concentration could substitute for the GnRHST in diagnosing and monitoring central precocious puberty (CPP) in girls. METHODS: Fifty-five girls with breast buds before 8 years of age were assessed by both the GnRHST and urinary gonadotropin assays. Based on the GnRHST results, 29 girls were assigned to the CPP group (peak LH≥5 IU/L), and 26 were placed in the premature thelarche (PT) group (peak LH<5 IU/L). Auxological data and urine and serum samples were collected at baseline and after treatment with a GnRH agonist for 12 and 24 weeks. RESULTS: Although the auxological data did not differ between the 2 groups, the serum levels of insulin-like growth factor-1, basal LH, follicle-stimulating hormone (FSH), estradiol, and peak LH; urinary LH; and peak serum LH/FSH and urinary LH/FSH ratios were higher in the CPP group than in the PT group. Pearson correlation analysis showed a positive correlation between the urinary and serum LH concentrations (r=0.660, P<0.001). Receiver-operating characteristic curve analyses showed that a urinary LH concentration of 0.725 IU/L was a cutoff that significantly predicted positivity on the GnRHST. Urinary LH and FSH concentrations declined significantly during GnRH agonist treatment. CONCLUSIONS: A single, random measurement of urinary gonadotropin concentration could be a reliable tool for initial screening and therapeutic monitoring of CPP in girls.