IMPE Abstracts

Objective: In girls, breast development under 8 years of age and peak serum luteinizing hormone (LH) is 5 IU/L or higher in gonadotropin releasing hormone (GnRH) stimulation tests is a standard method for diagnosing CPP. Because of higher body mass index (BMI) was associated with a lower LH response in the GnRH stimulation test, BMI should be considered when interpreting the result of GnRH stimulation tests. We aimed to find out whether changes in BMI affect the results of the GnRH stimulation tests.

Methods: We retrospectively reviewed the medical records of 962 girls under 9 years of age who visited our hospital due to breast development more than Tanner stage II and whose bone age was more than 1 year advanced than the chronological age and examined GnRH stimulation test twice or more. According to changing in BMI at the time of the first and last GnRH stimulation test, The patient were divided into 4 groups that normal to normal, normal to overweight/obesity (OWOB), OWOB to OWOB and OWOB to normal groups. We analyzed whether changes in BMI were a risk factor of the positive results in GnRH stimulation test using survival analysis and propotional hazard model.

Results: Mean age of total of 962 girls was 7.7 ± 0.7 years and the period between the first and last GnRH stimulation test was 212.2 ± 143.0 days. According to changing in BMI, the cases was divided into 4 groups that normal to normal (n=543), normal to OWOB (n=41), OWOB to OWOB (n=332), OWOB to normal (n=46). When the last test was performed, the cases in which positive result of GnRH stimulation test were 17.5%, 2.4%, 11.4%, 8.7% for each groups. Compared with the normal to normal group, adjusted hazard ratio positive result in GnRH stimulation test of normal to OWOB group was 0.09 (95% CI. 0.01-0.66, P=0.018). There was no difference of adjusted hazard ratio of positive result in GnRH stimulation test between OWOB to OWOB, OWOB to normal group and normal to normal group (P=0.262, P=0.441, respectively).

Conclusion: Our data suggests that interpretation of the GnRH stimulation test should be careful in weight gain patients from normal to overweight or obesity.