Antimullerian hormone
Antimullerian hormone (AMH) is a glycoprotein hormone belonging to the transforming growth factor-beta family that is produced by Sertoli cells of the testis in males and by ovarian granulosa cells in females. During male fetal development, expression of AMH prevents the mullerian ducts from developing into the uterus, resulting in development of the male reproductive tract. In females, the absence of AMH expression allows the mullerian ducts and structures to develop into the female reproductive tract.
In males, AMH serum concentrations are elevated in males under 2 years old and then gradually decrease until puberty, when there is a sharp decline. In females, AMH is produced by the granulosa cells of small growing follicles from the 36th week of gestation onwards until menopause when levels become undetectable.
Clinically, measurement of AMH is used clinically to assess gender in infants with ambiguous genitalia, premature ovarian failure, fertility, and as tumor marker for granulosa cell tumors of the ovary.
AMH measurements are commonly used to evaluate testicular presence and function in infants with intersex conditions or ambiguous genitalia. An AMH result above the normal female range is predictive of the presence of testicular tissue, while an undetectable value suggests its absence. In boys with cryptorchidism, a measurable AMH concentration is predictive of undescended testes, while an undetectable value is highly suggestive of anorchia or functional failure of the abnormally sited gonad. In mildly virilized females, AMH helps to differentiate between gonadal and nongonadal causes of virilization.
AMH is produced continuously by the granulosa cells of small growing follicles during the menstrual cycle and decreases as follicles go through the terminal stages of maturation. AMH provides a direct assessment of ovarian follicle reserve and is an important testfor evaluation of infertility. Because most fertility treatments rely on harvesting as many oocytes as possible, knowing the AMH before starting stimulation helps in medication management. Females with higher concentrations of AMH have a better response to ovarian stimulation and tend to produce more retrievable oocytes than females with low or undetectable AMH. Very low AMH levels (<1 ng/mL) in the setting of infertility are a poor prognostic indicator for a live birth when ovarian stimulation is used, either for in vitro fertilization or for superovulation. Very low AMH levels often require more aggressive ovarian stimulation protocols. In contrast, AMH concentrations exceeding 3 ng/mL may predict hyper-response to ovarian stimulation. For these patients, minimal stimulation is recommended.
AMH levels can also be used to predict which women are likely to have early (<45 years of age) or premature (<40 years of age) loss of ovarian function. Women with low AMH levels may be referred to a fertility specialist and may want to undergo egg retrieval and preservation. Menopausal women or women with premature ovarian failure of any cause, including cancer chemotherapy, have very low AMH levels, often below the assay detection limit of 0.1 ng/mL.
Polycystic ovarian syndrome can elevate serum AMH concentrations because it is associated with the presence of large numbers of small follicles. AMH concentrations may be 2- to 5-fold higher than age-appropriate reference range values. Such high levels predict anovulatory and irregular cycles.
Granulosa cell tumors comprise approximately 10% of ovarian tumors. Serum AMH concentrations are increased in some patients with ovarian granulosa cell tumors. AMH can be used as a tumor marker in addition to CA125 and inhibin A and B.
AMH concentrations are unaffected by pregnancy or use of oral or vaginal estrogen- or progestin-based contraceptives.
AMH is measured using an enzyme linked immunoassay. Specimen requirement is a red top tube of blood.
Reference range is gender and age specific.
