ESPE Abstracts (2016) 86 P-P1-755

Gonadotropin-Releasing Hormone Stimulation Test in Girls Younger than 3 Years Old: Does the Stimulated LH Greater Than 5 IU/l Always Mark Central Puberty Precoccious?

Gulcan Seymen Karabulut, Müge Atar, Filiz Çizmecioğlu & Şükrü Hatun

Kocaeli University Pediatric Endocrinology, Kocaeli, Turkey

Background: Premature thelarche is the isolated breast development in girls <8 years of age unaccompanied by other signs of puberty including advanced bone age or growth spurt. The GnRH stimulation test is used to distinguish between premature thelarche and central precocious puberty.

Objective and hypotheses: We studied accuracy of the gonadotropin responses to GnRH stimulation in predicting pubertal progression in children diagnosed with premature thelarche under the age of three.

Method: Data from thirty female patients under the age of 3 (20±7 months) diagnosed with premature thelarche was presented. At the time of diagnosis, the patients were evaluated based on the bone age, pelvic USG, and GnRH stimulation tests and those without pubertal progression during a minimum of 1 year follow up were included in the study.

Results: Among the patients, 26.6% of the patients (n=8) had Tanner stage 2 breast development while 73.3% had (n=22) Tanner stage 3. The bone age was within mean ±2S.D. for chronological age in all patients. Pelvic ultrasonography revealed no abnormality. In the GnRH stimulation test, the baseline median LH value was 0.29 (0.10–0.74) IU/l, baseline median FSH value was 4.96 (3.18–7.05) mIU/ml, the stimulated median LH value was 5.75 (3.31–8.58) IU/L, the stimulated mean FSH value was 40.38±20.37 mIU/ml and the stimulated mean LH/FSH ratio was 0.17±0.09. Among the patients, 33.3% (n=10) had baseline LH values >0.3 IU/l, 67% (n=20) had stimulated LH values >5 IU/l, 16.6% had (n=5) stimulated LH values >10 IU/l and the stimulated LH/FSH ratio in all the patients was below 0.66.

Conclusion: Although consensus statements define baseline LH values >0.3 IU/l, stimulated LH values >5 IU/l, and LH/FSH ratios >0.66 as diagnostic cut-offs for central precocious puberty, since the baseline and stimulated LH values in children under 3 years of age may be higher due to mini-puberty, these values do not help to distinguish between premature thelarche and central precocious puberty. Our results have demonstrated that the dominant FSH response to the GnRH stimulation and a LH/FSH ratio >0.66 are more valuable than the peak LH response in the differential diagnosis in these patient group.

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