Anti-Müllerian Hormone (AMH) was initially discovered for its embryological role in causing the regression of the female ducts to allow persistence and formation of internal male reproductive structures. More recently it has emerged as an excellent ovarian reserve test.
AMH is a dimeric glycoprotein which is produced by the granulosa cells in small ovarian follicles. In females, concentrations of the hormone rise steadily through adolescence to a peak in the mid-twenties, and subsequently decline until becoming undetectable in menopause. AMH has gained widespread attention for its utility in assessing a woman’s ovarian reserve. It can be measured before and after treatments known to be detrimental to the ovarian reserve, such as chemotherapy, pelvic irradiation and ovarian surgery. AMH is most commonly used for assessment and planning for fertility treatments such as in vitro fertilization (IVF).
In British Columbia and Alberta, patients can have the AMH blood test drawn at most public laboratories. In Alberta it is covered under provincial healthcare and in BC the patient must pay privately (Life Labs charges $70). Results are generally available within a week. AMH is not produced by the dominant follicle and therefore it remains stable throughout the menstrual cycle and can be accurately measured on any day. A small amount of intra-individual variability exists across menstrual cycles, although it is likely not substantial enough to warrant repeated measurement. Patients taking hormonal contraceptives can still have an accurate AMH measurement. Some research shows that long term oral contraceptive users’ AMH may be slightly depressed (~10%) but this is of undetermined clinical significance.
In Canada, AMH is reported in pmol/L. This can be converted to American units (ng/ml) by a conversion factor of 0.14. Many online sources report AMH in American units, so patients should use caution when trying to interpret their result. AMH must be interpreted in the context of patient age. Age-specific nomograms have been validated across the lifespan. A higher AMH level indicates a higher ovarian reserve. There is no AMH level that is diagnostic of polycystic ovary syndrome. A low AMH level (< 1.1ng/ml or 8pmol/L) is concerning for diminishing ovarian reserve.