Background: In adult women, serum levels of AMH reflect both the number of small growing follicles and remaining primordial follicles. AMH levels range 15 fold between healthy girls. Interpretation of AMH is contentious due to minor intra-individual changes around time of pubertal onset despite continuous loss of primordial follicles.
Objective and Hypotheses: To describe ovarian morphology (volume, follicles) in healthy girls and adolescents in relation to serum AMH levels.
Method: Nested cohort of 109 healthy peripubertal girls from The Copenhagen Mother-Child Cohort. Pubertal development by Tanners breast stage (B1 5). Ovarian morphology from a total of 87 scans with acceptable picture quality of both ovaries (B1,n=10; B2, n=20; B3, n=24; B4, n=30, B5, n=1; NA, n=2): volume (length×height×width×0.523); Follicle counts and measurements. Serum levels of AMH by ELISA (Beckman Coulter, generation I).
Results: Ovarian volume increased with age and pubertal progression (linear regression, beta 0.461, P<0.001 and 0.643, P<0.001, respectively), however, the initial increase in total number of follicles (median 14 follicles (B1) vs 23 (B3), P=0.001) levelled off (23 (B3) vs 20 (B4), P=0.247). Overall, the number of small follicles (24 mm) was positively associated with larger follicles (≥5 mm) (0.477, P<0.001), however, the ratio (small/larger follicles) declined through puberty (1.7 (B1) vs 0.8 (B4), P=0.038). Serum AMH reflects both ovarian volume and follicle numbers (0.261, P=0.015 and 0.525, P<0.001 respectively). Follicles of 23 mm and 45 mm were the main contributors to serum levels of AMH (multiple regression: β 0.344, P=0.002 and 0.235, P=0.041 respectively).
Conclusion: As in adult women, AMH is a quantitative marker of small growing follicles (follicles producing AMH). Equilibrium of follicle numbers in different stages suggests that inter-individual variation of AMH reflects variation in the number of primordial follicles even in girls and adolescents. Minor intra-individual changes of AMH levels in peripubertal girls can be explained by changes in the number of AMH producing follicles.
18 Sep 2014 - 20 Sep 2014