To the Editor:
Dr. Hadlow and colleagues argue that antimüllerian hormone (AMH) levels decrease in the luteal phase and that the hormone should be measured in the follicular phase, since this variability may lead to misprediction of ovarian response in IVF. This assumption was made on the basis of few, not frequent, blood samples performed on a very limited sample of women (1).
In the study, the intra-individual variability of AMH was found to be similar to that of FSH. This finding is really surprising and points out a critical revision of the results obtained. Both of the largest available studies to date (2, 3) reported that 89% of the variation in AMH was due to between-subjects variation, while only 11% was due to true individual fluctuations. AMH may exhibit some variability, but the important point is that the fluctuations are randomly distributed throughout the menstrual cycle (4), raising the possibility that a fixed day for its measurement, as proposed, would be useless. The suggested cyclic moifications of AMH in Dr. Hadlow’s study need to be confirmed in studies investigating hormonal variability through more frequent samples and across at least two menstrual cycles. A logical and agreeable hypothesis explaining why AMH should reduce in the luteal phase needed to be formulated by the authors. If AMH is produced by antral follicles, the number of which shows no significant reduction in the luteal phase, and since AMH seems to be only marginally influenced by gonadotropins, why should its concentration reduce in the second part of the cycle? Read the rest of this entry »