Auxological and metabolic parameters of children undergoing the gonadotropin-releasing hormone stimulation test: correlations with the final diagnosis of central precocious puberty in a single-center study

Background—Central precocious puberty (CPP) is characterized by clinical, biochemical, and ra-diological features similar to those of normal puberty, but CPP occurs before the age of eight in girls and before the age of nine in boys, subsequently leading to a reduction in the final body height in adulthood due to premature fusion of growth plates. The diagnosis of CPP is confirmed with a gonadotropin-releasing hormone (GnRH) stimulation test, which can lead to different interpreta-tions because the diagnostic peak levels of luteinizing hormone (LH) can vary. Patients and methods—This was a single-center, retrospective observational study investigating the possible correlation between gonadotropin peaks on the GnRH test and auxological, metabolic, and radi-ological parameters of patients evaluated for CPP. We collected and analyzed data from the medical records of children with suspected CPP over a period from January 2019 to July 2022 who underwent a GnRH test at the Fondazione Policlinico Universitario Agostino Gemelli in Rome, It-aly. Results—Our correlation analysis revealed no statistically significant differences in any aux-ological and radiological parameters. Among laboratory parameters, baseline levels of LH, folli-cle-stimulating hormone, sex hormone-binding globulin, and 17-beta estradiol were higher in children with a definitive diagnosis of CPP than in those with a negative GnRH test. In particular, the levels of LH at baseline and after the GnRH test were statistically significant in the group of CPP patients, consistent with the interpretation of the test. In the multivariate analysis, using a cut-off value of 4.1 IU/L, LH peaks showed both very high sensitivity (94%) and very high speci-ficity (95%); all other variables showed high specificity (90%) but unsatisfactory sensitivity. Con-clusion—Basal hormone dosages and, especially, basal levels of LH should be considered