To compare the clinical characteristics of peripheral precocious puberty (PPP) and central precocious puberty (CPP) girls with a basal luteinizing hormone (LH) level less than 0.1 IU/L to guide the reasonable clinical diagnosis of precocious puberty by the gonadotropin-releasing hormone (GnRH) stimulating test.

From February 2016 to August 2018, PPP girls (263 cases) and CPP girls (20 cases) with a basal LH value<0.1 IU/L who visited the Subei Hospital of Clinical Medical College of Yangzhou University were studied. Data were compared between groups, and logistic regression analysis was perform to identify the relevant risk factors and ROC curve was used to evaluate the diagnostic value of related indicators.

There were no significant differences between the PPP group and the CPP group in breast development age, age at visit, height at visit, body mass index, genetic target height, growth rate, endometrium appearance, proportion of>4 mm follicles, or basal FSH value. There were significant differences between the two groups in advanced bone age [(3.7±9.8) months vs (15.3±9.6) months, t=-4.908, P<0.001], ovary volume [1.1 (0.7, 1.7) ml vs 1.8 (1.3, 2.4) ml, Z=-3.916, P<0.001], uterine length [18 (16, 20) cm vs 21 (16, 24) cm, Z=-2.309, P=0.021], uterine volume [0.9 (0.6, 1.4) ml vs 1.3 (0.8, 2.4) ml, Z=-3.227, P=0.001], estradiol [18.4 (18.3, 25.3) pmol/L vs 33.3 (18.4, 43.0) pmol/L, Z=-3.182, P=0.001], and predicted compromised adult height (PAH-TH) [(-0.4±7.4) cm vs (5.5±5.7) cm, t=1.223, P=0.001]. Logistic regression analysis demonstrated that the months of advanced bone age (OR=0.844) and uterine volume (OR=0.330) were two independent risk factors for the diagnosis of CPP. ROC curve analysis showed that the area under the curve (AUC) of advanced bone age and uterine volume was 0.830 and 0.716, respectively. When the cutoff value for advanced bone age was 11.5 months, the sensitivity and specificity for diagnosis of CPP were 80.0% and 82.9%, respectively. When the cutoff value for uterine volume was 2.085 mL, the sensitivity and specificity for diagnosis of CPP were 45.0% and 95.1%, respectively.

The hypothalamic-pituitary-gonadal axis (HPGA) activation cannot be completely ruled out if basal LH is less than 0.1 IU/L. In these girls, GnRH stimulation test should be conducted to exclude CPP if the bone age is more than 11.5 months ahead or the uterine volume is greater than 2.085 ml.