Predictive factors for organic central precocious puberty and utility of simplified gonadotropin-releasing hormone tests

BACKGROUND: The aim of the present study was to determine whether the clinical presentation of patients with central precocious puberty (CPP) permits differentiation between idiopathic and organic forms, and to examine whether luteinizing hormone (LH) determination in single blood sample after gonadotropin-releasing hormone (GnRH) administration is sufficient to diagnose CPP. METHODS: Potential clinical and laboratory predictors for the presence of central nervous system (CNS) abnormalities were assessed. Sensitivities and specificities of LH and follicle-stimulating hormone (FSH) levels at 0, 15, 30, 60, 90 and 120 min were compared after GnRH stimulation. RESULTS: In 45 girls with signs of breast development, 26 were diagnosed as having CPP. The age of onset in patients with organic CPP was 4.75 +/- 2.01 years (range 1.2-7.1 years, median 5.0 years), whereas the age in patients with idiopathic CPP was 7.09 +/- 0.87 years (range 5.0-7.9 years, median 7.0 years). This parameter is the only one showing statistical significance. In addition, the specimen at 30 min after GnRH stimulation yielded highest sensitivity for the diagnosis of CPP. CONCLUSIONS: The earlier the onset of disease, the higher the possibility of presence of CNS lesion. According to the mean GnRH-stimulated LH levels and sensitivity at each time, a single blood sample obtained for LH determined after GnRH administration at 30 min can be used to diagnose CPP.