Anti-Mullerian Hormone (AMH)
What is AMH?
Anti-Mullerian Hormone (AMH) is a hormone produced by follicles in the ovary. The levels of AMH are highest in the least developed follicles – those that have the potential to produce more eggs. Its primary function appears to be the inhibition of excessive follicular development to maturity (i.e., it keeps egg production to a minimum).
The amount of AMH produced remains constant until early adulthood but declines rapidly from the age of 25, until levels reach zero at menopause. Levels of AMH appear high in conditions such as Polycystic Ovary Syndrome (PCOS), and lowest in women in menopause, or with ovarian failure.
What is the AMH Test (Egg Timer Test)?
The AMH test is a blood test, usually performed in conjunction with an antral follicle count, to predict Ovarian Reserve (i.e., how many eggs remain).
What’s a normal level of AMH?
AMH levels can be tested at any point in a woman’s cycle, because they remain constant and are not affected by other hormone levels. Since AMH is produced only in small ovarian follicles, blood levels can be used to measure the size of the pool of growing follicles in women. That is, it reflects the remaining egg reserve.
As women age, the number of remaining small follicles decreases, AMH levels fall, and fertility decreases.
Normal levels for fertile women are generally accepted to be between 14-30pmol/L.
Why should women be tested?
There are two main reasons women are tested:
- To determine current and future fertility status, or
- To determine a woman’s response to fertility medication.
For women who are keen to understand their current (and future) fertility, the test may help the decision regarding whether to delay starting a family.
The test may also be a useful diagnostic tool for patients at risk of diminished ovarian reserve (e.g., women with a history of ovarian failure, or a family history of early onset menopause, and women who have undergone chemotherapy or had ovarian surgery). As such, AMH may help to determine the need for fertility preservation strategies in these patients. It also provides a guide to ovarian reserve to identify women who should consider egg freezing.
For women undergoing fertility treatment, an AMH test can predict ovarian response to fertility medication. For example, low levels of AMH may indicate poor follicle reserves, requiring higher doses of fertility medication.
AMH testing also has the potential to influence clinical decisions about ovulation induction in IVF, as well as the number of embryos to be transferred.
Although AMH levels are a factor in successful pregnancy, they are not the sole indicator of your chances of conception. It is also recommended that “normal” results are considered with caution, and in conjunction with other factors, when considering your current and future fertility success.