AMH levels, measurable in serum, decline with age and are undetectable after menopause.10 Unlike FSH, which fluctuates during the menstrual cycle, AMH exhibits minimal intercycle and intracycle variation. The AMH level remains stable in women taking oral contraceptives and even in women who are pregnant.11
AMH is independently and significantly correlated with the ovarian response to gonadotropin therapy, with decreased levels of AMH associated with a poor response, and increased levels associated with a strong response.12 In the first cycle of IVF, an elevated AMH level has been associated with excessive response to gonadotropins and an increased risk of ovarian hyperstimulation syndrome (OHSS), independent of age and the presence of polycystic ovary syndrome.12
In a recent study of women who had an elevated FSH level and were undergoing IVF, the AMH level was strongly associated with the number of oocytes retrieved.13 Women who had an elevated FSH level but a serum AMH level of 0.6 ng/mL or above had a greater number of oocytes and day-3 embryos retrieved; they also had a lower cancellation rate than women who had a lower AMH level.13
Although no single test can predict the outcome of treatment for infertility, AMH concentrations are significantly higher in women who have a live birth (from the first cycle of stimulated IUI or after three cycles) than in women who do not.14
Two ELISA kits, one value?
Two types of enzyme-linked immunosorbent assay (ELISA) kits are commercially available for measurement of the AMH level: one from Immunotech Beckman Coulter and the other from Diagnostic Systems Laboratories. Neither kit has been approved for clinical use by the US Food and Drug Administration.
Studies comparing the values obtained using each kit have been inconsistent, generating controversy about the measurement of AMH. A recent study of women who were undergoing controlled ovarian stimulation found that the AMH levels obtained by the two kits were similar and significantly correlated with each other.15 In that study, the AMH level was measured on the day before gonadotropin administration or on the day of oocyte retrieval.15 In addition, the AMH concentrations measured by both kits were significantly associated with age, basal FSH levels, AFC, and the outcome of controlled ovarian stimulation.15 The authors concluded:
- The two commercially available kits provide reliable and similar results.
- The AMH level measured by either kit can predict the outcome of controlled ovarian stimulation, with similar reference values.15
Measurement of the AMH level can be an informative aspect of the evaluation of a patient’s fertility, as well as a valuable tool in the assessment of ovarian reserve. The AMH level can also help clinicians identify the appropriate dose of gonadotropins and predict which patients might be likely to over- or under-respond to stimulation—ultimately reducing the length and cost of treatment. Knowledge of the patient’s AMH level might inform pretreatment counseling and help women achieve reasonable expectations.
WHAT THIS EVIDENCE MEANS FOR PRACTICE
AMH is a useful test to help predict a patient’s response to ovarian stimulation and her chances of achieving pregnancy. However, AMH is only one measure of ovarian reserve and should not be used alone as a reason to exclude patients from treatment. In our practice, we use the AMH level along with cycle day 3 antral follicle count and FSH and estradiol levels.
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