What Can We Learn From Measuring AMH (anti-mullerian hormone)?
AMH is a hormonal study that is commonly ordered early in the infertility evaluation to as part of the assessment of ovarian function. More specifically the test provides some insight into the number of eggs available. When considered in the context of the ultrasound determined antral follicle count, cycle day 3 FSH (follicle stimulating hormone) and estradiol level, the AMH is a simple blood test that can contribute significantly to our understanding of a patient’s prospects for a live birth. It is particularly helpful in assessing the affects of age on ovarian function. One of the attractive features of this particular blood test is that it may be done at any time during the menstrual cycle as opposed to day 3 or 4, when the FSH and estradiol must be drawn.
Follicles (egg bearing structures within the ovary) may be thought of as being either resting and not growing (primordial) or growing (antral). AMH production is highest in the growing small follicles (less than 4mm in diameter), with smaller amounts of AMH produced as the follicles enlarge and mature.
We have learned that a greater number of growing small follicles, the higher the AMH value. It has also been demonstrated that the size of the growing group of follicles is reflective of the total number of remaining resting or primordial follicles. It is this relationship that has led to the use of AMH levels as one of the tests for ovarian reserve. As women age, the number of resting follicles available to become growing follicles decreases, and this is reflected in decreasing AMH levels.
Since AMH testing has not been available clinically for nearly as long as FSH and estradiol testing, our interpretation of AMH values is still evolving. At the present time, the values below offer some guidelines:
Very Low Less than .3 ng/ml
Low .3 -.6 ng/ml
Low Normal .7 - .9 ng/ml
Normal Greater than 1.0 ng/ml
High Greater than 3.0 ng/ml
AMH (anti-mullerian hormone) testing has become popular as one of the available tests for evaluation of ovarian reserve. The test is reflective of the number of resting follicles remaining in the ovary and does physiologically decrease with age. It is useful as an indicator of how many eggs are available and provides an excellent indication of how a given patient might respond to ovarian stimulation for IVF. When considered as one of several indicators of ovarian reserve including the antral follicle count, and day 3 FSH/estradiol levels, it enhances our ability to predict a given patient’s response to controlled ovarian stimulation. As additional large studies looking at AMH levels are published we may be able to use this test as a reliable predictor of extremely poor outcomes. Additionally, since high AMH levels are associated with polycystic ovarian syndrome, the test may have predictive value for ovarian hyperstimulation syndrome. We should be able to use AMH levels to choose appropriate gonadotropin doses especially in PCOS patients. Although there is very little data available at the present time, it may very well be that PCOS patients, who retain high antral follicle counts as they age, may have greater fertility potential compared to non-PCOS patients of similar age.