AMH Test

Anti-Müllerian hormone (AMH) is a protein made by specific cells in the ovaries called granulosa cells and, in men, by Sertoli cells in the testes. Its name comes from its early role in fetal development: in male embryos, AMH signals the regression of the Müllerian ducts, which would otherwise form the uterus and fallopian tubes. This action helps steer male reproductive development.

In adult women, AMH takes on a very different function. It helps regulate folliculogenesis, the process by which immature ovarian follicles develop into eggs. AMH slows down the recruitment of resting follicles and reduces their sensitivity to follicle-stimulating hormone (FSH). In this way, it acts as a kind of “brake” on egg development, preserving the ovarian reserve over time. Because AMH levels reflect the number of developing follicles, it has become one of the most reliable markers for assessing ovarian reserve and predicting how someone might respond to fertility treatments such as in vitro fertilization (IVF).

Clinically, low AMH levels may suggest a reduced egg supply and can be an early indicator of menopause transition. Very high AMH levels are often seen in polycystic ovary syndrome (PCOS), a condition characterized by irregular cycles, excess androgens, and metabolic disturbances. In PCOS, measuring AMH may eventually become as useful as or even replace ultrasound for diagnosis, although standardization of testing is still needed.

That said, AMH is not a perfect reflection of fertility on its own. For example, women with normal AMH levels can still face infertility for other reasons, and women with low AMH can sometimes conceive naturally. Additionally, AMH measurements can vary between different laboratories due to assay differences, which means results should always be interpreted in context.

Beyond reproduction, AMH appears to play roles in the brain and endocrine system. Recent studies suggest it may influence the hypothalamic-pituitary-gonadal axis (the hormonal circuit that regulates fertility), as well as learning, memory, and possibly protection against conditions like Alzheimer’s disease. AMH and its receptor are also being investigated as potential targets in cancer diagnostics and therapies, particularly in ovarian and other reproductive cancers.