Adequacy of basal luteinizing hormone levels in the diagnosis of central precocious puberty

AIM: To determine the clinical, anthropometric, and laboratory parameters that could be used for differentiating central precocious puberty from premature thelarche in girls who had breast development between the ages of 3 and 8 years. MATERIAL AND METHODS: The study included 344 girls (196 girls with idiopathic central precocious puberty, 148 girls with premature thelarche) who underwent gonadotropin- releasing hormone stimulation tests for breast development. Age at diagnosis, bone age, anthropometric measurements, basal/stimulated hormone levels were recorded. Univariate regression analysis was performed to determine the parameters that could be used for differentiating precocious puberty from premature thelarche. Significant parameters in univariate analyses were grouped according to the thresholds determined using receiver operating characteristic curves and reevaluated through multivariate analysis. RESULTS: The bone age, height-standard deviation score, body mass index-standard deviation score, and growth velocity-standard deviation score at diagnosis were found to be higher; pubertal stages were found to be more advanced; uterus and ovary volumes were found to be larger; and the basal/peak luteinizing hormone, follicle-stimulating hormone, luteinizing hormone/follicle-stimulating hormone levels were found to be higher in the subjects with precocious puberty. There was no difference between estradiol levels between the two groups. The best thresholds to differentiate the two groups were found as 0.65 IU/L (78% sensitivity, 100% specificity), 1.9 IU/L (100% sensitivity, 72% specificity), 0.25 (67% sensitivity, 100% specificity) and 1.1 (69% sensitivity, 71% specificity), respectively, for basal luteinizing hormone, follicle-stimulating hormone, luteinizing hormone/follicle-stimulating hormone ratio, and the growth velocity-standard deviation score. CONCLUSION: In girls presenting with early breast development, a basal luteinizing hormone level of ≥0.65 IU/L and a luteinizing hormone/follicle-stimulating hormone ratio of ≥0.25 are sensitive ways to demonstrate activation of the hypothalamo-pituitary-gonadal axis. Among these, the variable that gives the best sensitivity and specificity is the measurement of basal luteinizing hormone levels (≥0.65 IU/L), which can be used as a screening test in the diagnosis of central precocious puberty.