Girls with premature thelarche younger than 3 years of age might have stimulated LH greater than 10 IU/L

Abstract

Introduction: Premature thelarche (PT) is the isolated breast development in girls prior to 8 years of age. Gonadotropin-releasing hormone (GnRH) stimulation test is sometimes used to distinguish between PT and central precocious puberty (CPP) although the interpretation of the test in early ages is challenging. The objective of this study is to determine the FSH and LH responses to GnRH stimulation in girls below 3 years of age with PT. Method: A standardized GnRH stimulation test, bone age and pelvic ultrasound were evaluated and those without pubertal progression after a minimum of one-year follow up were included in the study. Results: In the GnRH stimulation test, the baseline median LH was 0.29 (0.10- 0.74) IU/L, baseline median FSH was 4.96(3.18-7.05) mIU/mL, the peak median LH was 5.75 (3.31-8.58) IU/L, the peak mean FSH was 40.38 ± 20.37 mIU/mL. Among uncorrected proof the patients, 33.3% (n=10) had baseline LH > 0.3 IU/L, 67% (n=20) had peak LH > 5 IU/l and 16.6% (n=5) >10 IU/L. The peak LH/FSH ratio was 0.17 ± 0.09 and ≤ 0.43 in all participants. Conclusion: Although consensus statements usually define baseline LH >0.3-0.5 IU/L, peak LH >5 IU/L, and LH/FSH ratios >0.66-1.0 as diagnostic cut-offs for CPP, in children below 3 years of age, the baseline and peak LH values may be detected pubertal, possibly due to mini-puberty. The dominant FSH response in the GnRH stimulation test is more valuable than the peak LH response in the diagnosis of PT.