Objective:To investigate the diagnostic value and cutoff value of the basal luteinizing hormone (LH) level for central precocious puberty (CPP) in girls with different body mass index (BMI) values.Methods:A total of 1 087 girls aged 6 to 8 years old with breast development and visiting the Department of Endocrine Genetics and Metabolism, Fuzhou Children′s Hospital of Fujian Medical University from January 2014 to December 2018 were enrolled.The girls had the breast development of Tanner stage B2 or B3.They were divided into groups of normal weight (840 cases), overweight (133 cases) and obesity (114 cases) according to BMI percentiles corresponding to their age and sex.All individuals underwent gonadotropin-releasing hormone (GnRH) agonist test.Statistical analysis was performed using SPSS 18.0 software, and the receiver operating characteristic (ROC) curve was drawn.Results:In the normal weight group, 393 girls were positive and 447 girls were negative for GnRH test.In the overweight group, 72 girls were positive and 61 girls were negative for GnRH test.In the obesity group, 40 girls were positive and 74 girls were negative for GnRH test.The areas under the ROC curve (AUC) of the basal LH level for the diagnosis of CPP in the normal weight, overweight, and obese girls were 0.826, 0.774, and 0.801, respectively.When the Youden index was maximum, the cutoff values of the basal LH level were 0.245 IU/L, 0.225 IU/L and 0.145 IU/L, respectively; the sensitivities were 63.9%, 65.3%, and 80.0%, respectively; the specificities were 87.9%, 82.0%, and 71.6%, respectively.When the cutoff value of the basal LH level was 0.455 IU/L in the normal weight group, 0.480 IU/L in the overweight group, and 0.335 IU/L in the obesity group, the specificities of the 3 groups were all above 96.6%.Conclusions:It is reliable to use the basal LH level for CPP diagnosis for girls with different BMI values.The cutoff value of the basal LH level for CPP diagnosis in obese girls is the lowest.