Individual serum levels of anti-Müllerian hormone in healthy girls persist through childhood and adolescence: a longitudinal cohort study.

BACKGROUND: In adult women, the circulating level of anti-Müllerian hormone (AMH) is a novel marker of ovarian function, as it reflects the number of remaining ovarian follicles. Therefore, AMH has gained widespread attention in fertility clinics, and a low AMH is believed to predict impaired fertility and imminent menopause. However, the natural course of circulating AMH levels during female childhood and adolescence is not known.
METHODS: Serum levels of AMH and FSH were measured in girls participating in The COPENHAGEN Puberty Study. Longitudinal part: 85 healthy girls and adolescents were examined, and blood samples were drawn every 6 months for an average of 3 years: median (range) number of samples per girl was 6 (2-10), age at baseline was 9.2 (5.9-12.9) years. Cross-sectional part: 224 prepubertal girls (age 8.3, 5.6-11.7 years) were examined and each girl had one blood sample drawn.
RESULTS: The individual mean AMH levels in girls followed longitudinally ranged from 5 to 54 pmol/l (median 18 pmol/l). The mean intra-individual coefficient of variation of AMH was 22% (range 0-54%). Overall, each girl maintained her AMH level throughout childhood and adolescence although minor, but significant, changes occurred during pubertal transition. In prepubertal girls, AMH was negatively correlated with FSH (r = -0.31, P < 0.001). Twelve per cent (10/85) had mean AMH below a cut-off value of 8 pmol/l, indicating that the interpretation of low AMH as a marker of approaching menopause may not apply to pre- and peri-pubertal girls.
CONCLUSIONS: Circulating AMH exhibits only minor fluctuations during childhood and adolescence, and a random AMH measurement seems representative for a given girl. The negative AMH-FSH correlation in prepubertal girls supports the notion that AMH is a quantitative marker of ovarian follicles even in young girls.