Impact of BMI on gonadorelin-stimulated LH peak in premenarcheal girls with idiopathic central precocious puberty.

OBJECTIVE: To clarify the impact of body mass index (BMI) on luteinizing hormone (LH) secretion in response to gonadorelin (GnRH) stimulation testing in girls diagnosed with idiopathic central precocious puberty (ICPP).

METHODS: Retrospective single-center cohort study was carried out in 865 confirmed ICPP girls who underwent GnRH stimulation tests. Pubertal development according to Tanner, sex hormone parameters, and LH secretion in response to GnRH-stimulation was compared.

RESULTS: Around 609 girls were of normal weight (70.4%), while 168 children (19.4%) were overweight, and 88 (10.2%) were obese. Peak LH levels after GnRH were much higher in the normal-weight group, with a median of 9.1 mIU ml(-1) (interquartile 5.2-13.1), compared with the median peak LH in the overweight and obese groups (8.5 mIU ml(-1), interquartile 5.3-11.6, and 6.2 mIU ml(-1), interquartile 5.3-11.0, respectively P < 0.001 for all comparisons). Peak LH/FSH ratio was also lower in the obese group (median 0.6, interquartile 0.68-0.90) compared with the normal-weight (median 0.8, interquartile 0.61-1.11) and overweight (median 0.8, interquartile 0.64-0.92) groups.

CONCLUSIONS: Higher BMI is associated with lower LH response to GnRH-stimulation testing in girls with ICPP. It is recommended that BMI should be considered when interpreting GnRH-stimulation tests.