Anti-Müllerian hormone levels in the spontaneous menstrual cycle do not show substantial fluctuation

Anti-Müllerian hormone (AMH), a quantitative marker for ovarian reserve, has been suggested to be independent of the classical endocrine fluctuations of the menstrual cycle. The objective of the study was to determine whether AMH levels are constant throughout the menstrual cycle, compared with those of FSH, LH, and estradiol. Frequent blood sampling was performed in 44 fertile, regularly cycling, female volunteers during one full menstrual cycle. The study was conducted at a university hospital. AMH, FSH, LH, and estradiol measurements were allocated to one of seven cycle phases, and a multilevel analysis was performed. Consistent fluctuation patterns were tested by fitting sine patterns to the data. Finally, the frequency in which randomly selected individual samples would remain in one of five preset level categories (quintiles) for each of the variables was studied. A sine pattern fitted to the AMH data was not statistically significant (P = 0.40). In contrast, sine patterns for FSH, LH, and estradiol were highly significant. Comparing the seven cycle phases, no significant differences could be observed between phase-specific AMH levels (P = 0.06). Repeated selection of AMH samples for each individual showed that in 71.5% of selections, AMH values remained in the same quintile, whereas in 27.9% values fell in an adjacent quintile. AMH levels measured through a full menstrual cycle did not show consistent fluctuation patterns in contrast to levels of FSH, LH, and estradiol. Furthermore, random fluctuations were small, indicating that AMH can be relied on as a cycle-independent marker for ovarian reserv