Whatever its variability, AMH remains the most stable hormonal predictor

8 04 2013

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?

No less important is understanding whether the proposed variability in AMH throughout the menstrual cycle is clinically acceptable or not. To answer this question, Dr. Hadlow and colleagues calculated whether AMH values crossed the cut-off values proposed by others for the categorization of ovarian response in IVF. They found that throughout the menstrual cycle, 7 out of 12 women crossed the cut-off values for the predicted response category, hence concluding that variability in AMH may lead to misclassification in as high as 58% of patients. However, whether samples will cross an absolute threshold is not surprising as there will always be variability in any assay and therefore a value may go above or below it even on repeated measurements on the same day due to intra- and inter-assay variations.

The real effect of AMH variability should be tested in the clinical setting. When considering studies based on a random AMH measurement in order to predict ovarian response to FSH, the authors could confirm a strong association of random AMH with the oocyte yield and an accurate prediction of both poor and high response. In particular, the use of a random AMH measurement leads to the correct categorization of 75% of patients (5), which is very different from what Dr. Hadlow concluded.

AMH still remains the most stable ovarian hormone and the best hormonal predictor in IVF with the not negligible advantage of being randomly measurable.

Antonio La Marca, M.D., Ph.D.
Mother-Infant Department, Institute of Obstetrics and Gynecology,
University of Modena and Reggio Emilia, Modena, Italy

References

1. Hadlow N, Longhurst K, McClements A, Natalwala J, Brown SJ, Matson PL. Variation in antimüllerian hormone concentration during the menstrual cycle may change the clinical classification of the ovarian response. Fertil Steril. 2013 Feb 21 [Epub ahead of print].

2. van Disseldorp J, Lambalk CB, Kwee J, Looman CW, Eijkemans MJ, Fauser BC, et al. Comparison of inter- and intra-cycle variability of anti-Mullerian hormone and antral follicle counts. Hum Reprod 2010;25:221-7.

3. Fanchin R, Taieb J, Lozano DH, Ducot B, Frydman R, Bouyer J. High reproducibility of serum anti-Mullerian hormone measurements suggests a multi-staged follicular secretion and strengthens its role in the assessment of ovarian follicular status. Hum Reprod 2005;20:923-7.

4. Hehenkamp WJ, Looman CW, Themmen AP, de Jong FH, Te Velde ER, Broekmans FJ. Anti-Müllerian hormone levels in the spontaneous menstrual cycle do not show substantial fluctuation. J Clin Endocrinol Metab 2006;91:4057-63.

5. Nelson SM, Yates RW, Fleming R. Serum anti-Müllerian hormone and FSH: prediction of live birth and extremes of response in stimulated cycles-implications for individualization of therapy. Hum Reprod 2007;22:2414-21.

Published online in Fertility and Sterility doi:10.1016/j.fertnstert.2013.04.010

The authors respond:

The finding of higher antimüllerian hormone (AMH) in the follicular phase compared with the luteal phase of menstrual cycle is not novel, with Sowers et al. (1) noting a follicular phase rise of AMH in younger women, and Wunder et al. (2) noting maximum AMH levels in late follicular phase and lowest AMH in early luteal phase in a study of 36 healthy young women. Differentiating women with normal and reduced ovarian reserve is critical in analysis, as demonstrated by Sowers et al. (1) and reflects the approach of our study.

Regarding intra-individual variation and the debate over the expected variation throughout cycle, this has similarly been shown to alter depending on the women analyzed (3). When data that have previously reported no significant cyclic variation in a group was re-analyzed in individuals by Overbeek et al. (3), significant intra-cycle variation was found and was greatest in younger women. While not expressed in terms of intra- and inter-individual percentage variation, Overbeek et al. showed that young women with a mean (sd) AMH of 1.63 (0.87) ug/L had an average absolute AMH difference of 0.81 ug/L (50% of the mean AMH), with differences ranging potentially as high as 2 ug/L (mean +/-sd = 0.81 + 0.59) (3). Variation in younger women was significantly greater than in older women, who had an average absolute AMH difference of 0.31 ug/L, only 19% of the 1.64 ug/L mean AMH. This lower result among older women may be more reflective of the values cited by La Marca et al. Our study only included women with at least one AMH value indicating adequate ovarian reserve, and as such our findings are more consistent with Overbeek et al.’s younger group. Further, it is not feasible to attribute this degree of variation to intra- or inter-assay variation as our inter-assay CV’s were good at <5.5% across 6 months, a finding replicated in several other studies.

It is suggested that we should provide an agreeable hypothesis as to why AMH may be higher in the follicular phase given that AMH is produced by antral follicles whose numbers do not change throughout the cycle. We do not believe it is the role of a pilot study to provide mechanisms for a finding. However, we would note that others have already shown that antral follicle count is not the only factor predicting AMH, but that gonadotropins and follicular recruitment (4, 5) may have important roles to play.

Whether the follicular phase is the best time to assess AMH remains to be confirmed, as stated in our manuscript. We concur with the comments of Overbeek et al., who noted that "AMH can fluctuate substantially in younger women throughout menstrual cycle" and that "large inter-individual variations in AMH concentrations mean the accuracy of a single measurement as a marker for ovarian reserve could be unreliable" (3). Last, we agree with Dr. LaMarca that AMH remains the best hormonal predictor of IVF, but would caution that a single result in a young woman should be interpreted with caution in light of our and others’ findings.

Narelle C. Hadlow, M.B.B.S., F.R.C.P.A.
Suzanne J. Brown, B.Sc. (Hons)
Western Diagnostic Pathology, Myaree, Western Australia

References

1. Sowers M, McConnell D, Gast K, Zheng H, Nan B, McCarthy JD, et al. Anti-Müllerian hormone and inhibin B variability during normal menstrual cycles. Fertil Steril 2010;94:1482-6.

2. Wunder DM, Bersinger NA, Yared M, Kretschmer R, Birkhäuser MH. Statistically significant changes of antimüllerian hormone and inhibin levels during the physiologic menstrual cycle in reproductive age women. Fertil Steril 2008;89:927-33.

3. Overbeek A, Broekmans FJ, Hehenkamp WJ, Wijdeveld ME, van Disseldorp J, van Dulmen-den Broeder E, et al. Intra-cycle fluctuations of anti-mullerian hormone in normal women with regular cycle: a re-analysis. Reprod BioMed Online 2012;24:664-69.

4. Tran ND, Cedars MI, Rosen MP. The Role of Anti-Müllerian Hormone (AMH) in Assessing Ovarian Reserve. J Clin Endocrinol Metab 2011;96:3609-14.

5. Sonntag B, Nawroth F, Ludwig M, Bullmann C. Anti-mullerian hormone in women with hypopituitarism diagnosed before or during adolescence. Reprod BioMed Online 2012;25:190-92.

Published online in Fertility and Sterility doi:10.1016/j.fertnstert.2013.04.012

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