The Influence of Body Mass Index on Luteinizing Hormone Levels after Gonadotropin-Releasing Hormone Stimulation in Girls with Precocious and Advanced Puberty

ABSTRACT

PURPOSE: The aim of this study was to investigate the influence of body mass index (BMI) on the level of peak luteinizing hormone (LH) after gonadotropin-releasing hormone (GnRH) stimulation in girls with central precocious puberty (CPP) and advanced puberty (AP). METHODS: This study conducted a retrospective review of the medical records of 113 girls (7 to 9 years old; 24 CPP, 89 AP) who underwent a GnRH stimulation test. The following parameters were evaluated chronologic age (CA), bone age (BA), the difference between BA and CA (BA-CA), height, weight, BMI, and the levels of basal LH, peak LH, basal follicle stimulating hormone (FSH), peak FSH, and basal estradiol. RESULTS: The peak LH level was negatively correlated with weight-standard deviation score (SDS) and BMI-SDS; furthermore, the peak LH level was positively correlated with both basal and peak FSH levels. Using multivariate analysis, BMI-SDS was found to be a significant factor in predicting peak LH levels after GnRH administration. When the subjects were divided into four groups by quartile of peak LH level, the mean BMI-SDS of the highest LH group was significantly lower than the mean BMI-SDS of the lowest LH group. CONCLUSION: LH levels rise after GnRH administration is blunted in precocious and advanced pubertal girls with high BMI. The impact of BMI on the GnRH stimulation test should be considered when evaluating sexual precocity in girls.