AMH

What it is

AMH (Anti-Müllerian Hormone) is a protein produced by the granulosa cells of small ovarian follicles. It reflects the number of follicles available at a given time — what is called the ovarian reserve. Unlike other hormones such as FSH or oestradiol, AMH varies little throughout the cycle, making it a practical marker: it can be measured at any point in the cycle.

Reference values vary by age and laboratory. They naturally decline with age, reflecting the gradual reduction in follicular reserve.

Why it matters in PCOS

In PCOS, AMH is often significantly elevated — sometimes 2 to 3 times higher than usual values for the patient's age. The reason is mechanical: PCOS is characterised by a large number of small antral follicles (visible on pelvic ultrasound). Since each of these follicles produces AMH, the combined level is high.

Since 2023, the Monash University international guideline notes that an elevated AMH threshold can, in certain contexts and with calibrated laboratories, replace the antral follicle count on ultrasound as the morphological criterion for the Rotterdam diagnostic criteria. This remains subject to local laboratory validation.

What AMH does not tell you

A high AMH in PCOS does not mean infertility. It indicates a large number of follicles, but not their ability to ovulate spontaneously or in response to treatment. Many people with PCOS and very high AMH conceive naturally or with minimal stimulation.

Conversely, a low-normal AMH in someone with PCOS does not necessarily change the diagnosis or the options available.

AMH values are not interpreted in isolation: they fit into a complete clinical picture (symptoms, cycles, hormone panel, life goals) that only your doctor can evaluate.

Key takeaways

• Produced by small ovarian follicles — reflects follicular reserve
• Often elevated in PCOS due to the large number of follicles
• Can be measured at any point in the cycle
• High AMH ≠ automatic infertility
• Always interpret with your doctor, in context