Intra-cycle fluctuations of anti-Müllerian hormone in normal women with a regular cycle: a re-analysis.

Anti-Müllerian hormone (AMH) has emerged as an important marker of ovarian reserve. Its variation throughout the cycle, however, may still be a matter of debate. The objective of this study was to re-evaluate the intra-cycle fluctuations of AMH in individuals in a prospective clinical study with focus on the age-related effects on these fluctuations. Frequent blood samples were obtained from the mid-luteal phase of the first cycle to the mid-luteal phase of the second cycle in 44 healthy, regularly menstruating Caucasian women. Main outcome measures were individual fluctuations of AMH concentrations during the natural menstrual cycle. AMH concentrations exhibited large fluctuations throughout the cycle and did not follow a defined pattern. Female age was negatively correlated with mean AMH concentrations. The absolute intra-individual variation was also negatively associated with age, whereas the relative intra-individual variation was positively associated with age. Although the fluctuation in relative intra-individual variation was higher in the older group, the absolute variation is very low and these fluctuations might therefore be of limited clinical relevance in this age group. These data show that in younger women caution should be exerted with the interpretation of a single randomly taken AMH measurement as a representative of ovarian reserve.