The source of Anti Mullerian Hormone (AMH) is the granulosa cells that line the egg sacs in the ovarian follicles. These cells secrete AMH during the pre-antral stages of follicular growth. AMH secretion stops when the growing follicles develop into antral follicles (size 8mm). AMH secretions are not influenced by gonadotrophins. Therefore AMH levels are fairly constant and can be measured anytime during the woman’s cycle.
Measuring the AMH levels helps in two important ways:
1. AMH measures the ovarian reserve, hence it can reassure women about their ovarian reserve especially if they want to delay starting a family. Alternately, it can help screen women with poor ovarian reserve who should not delay in starting a family.
A number of Follicles are recruited each menstrual cycle, from a pool of egg precursors called primordial follicles in the ovaries also called the ovarian reserve. As the ovarian reserve declines, the number of follicles recruited also drops. Since the number of follicles recruited in each cycle is depend on the number of remaining egg precursors in the ovarian pool, the AMH secretion is proportionate to the size of the remaining primordial follicles or the ovarian reserve.
2. AMH test in correlation with other assessment parameters helps in understanding how a woman will respond to stimulation drugs. Predicting the Ovarian response before the treatment helps doctors make an informed decision about the treatment protocol which impacts the cycle’s outcome.
Before AMH tests, the only way to understand how a woman would respond to stimulation drugs was to make them go through one stimulation cycle. But that entire process can be avoided now by doing a simple AMH test. This is especially important because AMH levels are high in women with PCOS and these women may have a risk of Ovarian Hyper Stimulation Syndrome (OHSS). Similarly AMH is low in women with poor ovarian reserve so for these woman the stimulation protocol has to be adjusted to get a better response.
The most important test characteristic of a screening test is its predictive value rather than sensitivity or specificity. The AMH reference range for normal cut off values are between 1-4ng/ml. Low AMH cut off points are specific for poor response.
|Interpretation (women < 35 yrs)||AMH Blood Level|
|High (often PCOS)||Over 4.0 ng/ml|
|Normal||1.5 - 4.0 ng/ml|
|Low Normal Range||1.0 - 1.5 ng/ml|
|Low||0.5 - 1.0 ng/ml|