Determination of anti mullerian hormone and inhibin B reference ranges according to pubertal stages in children and adolescent girls

Introduction and Objective: Anti Mullerian hormone (AMH) and inhibin B, both secreted by granulosa cells, play crucial roles in pubertal development and reflecting ovarian reserve. Establishing reference intervals for AMH and inhibin B across different pubertal stages is essential for assessing ovarian function and identifying potential reproductive health issues early. This study aims to establish these reference intervals, reflecting ovarian reserve in children and adolescent girls. Method: This prospective study included 320 healthy females aged 6-18 years from Cerrahpasa Medical Faculty (2023-2024). Blood samples were collected to measure LH, FSH, estradiol, inhibin B, and AMH levels, and antral follicle counts were determined by transabdominal ultrasound in cases with AMH <1.1 ng/mL. Exclusion criteria included recent illness, medication, hormonal treatments, ovarian surgery, metabolic diseases, syndromic conditions, and chemotherapy or radiotherapy history, ensuring a healthy cohort for accurate reference intervals (RI). Results: The mean age of participants was 11,63 ± 3,24 years. AMH and Inhibin B levels significantly increased with age. While low AMH levels in the prepubertal period indicate low follicular activity and an inactive ovarian reserve, AMH levels were observed to increase in stage 2. A slight decrease was noted in stage 3, followed by an increase in stages 4 and 5. In our study, Inhibin B values showed a significant increase during the pubertal development process. The median inhibin B level, which was quite low in pubertal stage 1 (9.6 pg/mL), was observed to gradually increase up to stage 5. Particularly in stage 4 (39.75 pg/mL), inhibin B levels reached high levels, and in pubertal stage 5 (39.5 pg/mL), they remained at similar levels. This increase in the later stages of puberty was found to be related to the response of the follicles in the ovary to FSH and their growth. While there was no difference in AMH between the prepubertal and postpubertal periods, significant increases were observed in Inhibin B, FSH, LH, and estradiol levels in the postpubertal period. In the entire patient group, AMH showed a positive correlation with AFC, while a statistically significant difference was found between AFC and inhibin B in the group with AMH <1.1 ng/mL. When comparing the groups with AMH <1.1 ng/mL and AMH >1.1 ng/mL, AFC counts were found to be significantly lower in the group with AMH <1.1 ng/mL. According to ROC analysis, the threshold value for AMH in the diagnosis of ovarian insufficiency was determined to be 1.195 ng/mL, while no threshold value was determined for inhibin B. Conclusion: Although there are studies reporting reference values for AMH levels according to age groups in childhood and adolescence, our study is the first to evaluate AMH reference ranges according to pubertal stages. In conclusion, it was found that AMH and AFC together provide stronger results in predicting ovarian reserve, and including inhibin B in this evaluation could contribute to assessing fertility potential, especially in patients with low ovarian reserve. Keywords: Puberty, AMH, Inhibin B