AMH (anti-Mullerian hormone)

The range falls steadily with age (for example roughly 9 to 84 pmol/L in the early twenties, 7 to 76 in the late twenties, 4 to 58 in the early thirties and 1 to 40 in the early forties), so labs print age-banded ranges and the printed one is the one to use.

AMH is a hormone made by the small developing follicles in the ovary. Because the number of these follicles reflects the pool of eggs remaining, AMH is used as a marker of what is called ovarian reserve. It falls gradually with age and reaches very low levels around the menopause. In men it is made by the testes and is occasionally measured in boys.

It is requested in fertility clinics to help plan IVF and to gauge how the ovaries are likely to respond to stimulation, when early menopause is being looked into, in polycystic ovary syndrome, and it is a common item on private fertility panels. It does not say whether someone will conceive naturally.

• Polycystic ovary syndrome, where there are many small follicles
• Younger age, in the general population
• Rarely, a type of ovarian tumour called a granulosa cell tumour
• Vitamin D supplements, slightly, in some studies

• Older age, gradually and then steeply from the late thirties
• The menopause and the years before it
• Chemotherapy, radiotherapy or ovarian surgery
• The combined contraceptive pill and other hormonal contraception, reversibly by around a fifth to a third
• Smoking
• Some inherited and autoimmune conditions affecting the ovaries

• Hormonal contraception lowers it while it is being taken and it recovers after stopping
• Different assays and generations of the same assay give different numbers, so results from two labs are not comparable
• It is a guide to egg numbers, not egg quality, and low values are common in healthy women approaching forty

It can be taken on any day of the cycle and needs no fasting. Ideally taken off hormonal contraception for a couple of months. Assays differ, so repeat tests are best done in the same laboratory.

Written by a UK consultant physician. Typical UK adult reference ranges; your laboratory's own printed range takes precedence.