AMH (Anti Mullerian Hormone)

Overview

Anti-Müllerian Hormone (AMH) is a peptide growth factor produced by granulosa cells in ovarian follicles (and by Sertoli cells in males). AMH serves as a reliable marker of ovarian reserve because it reflects the quantity of antral and pre-antral follicles available for recruitment. Unlike many reproductive hormones, AMH levels remain relatively stable across the menstrual cycle, making measurement convenient and clinically informative. Clinicians use AMH to predict ovarian response to stimulation, estimate remaining reproductive lifespan, help diagnose polycystic ovary syndrome (PCOS), detect premature ovarian insufficiency, guide in vitro fertilization (IVF) protocols, and counsel on fertility potential. In males, AMH testing evaluates Sertoli cell function and assists in diagnosing certain disorders of sex development.

Symptoms

AMH itself does not cause symptoms, but abnormal AMH levels are associated with recognizable clinical pictures:

1. Low AMH (poor ovarian reserve): Women may notice irregular or shortened menstrual cycles, difficulty conceiving, or poor response to fertility treatments. Low AMH is often an early biochemical sign preceding visible menopausal symptoms.
2. High AMH (excess follicle pool): Elevated AMH commonly correlates with PCOS, whose features include irregular cycles, acne, excessive hair growth, weight gain, and subfertility. Very high AMH can also indicate granulosa cell tumors, which may present with menstrual irregularities, abdominal discomfort, or signs of estrogen excess.
3. In males: Low or absent AMH may be suspected in infants or children with ambiguous genitalia, undescended testes, or delayed puberty; clinical signs vary by condition.

Causes

AMH levels change due to a range of physiological and pathological mechanisms:

1. Physiologic decline with age: The primary cause of falling AMH is the natural depletion of the ovarian follicle pool as women age; levels progressively decline toward menopause.
2. Ovarian damage or loss: Surgery, severe infection, chemotherapy, radiation, or endometriosis can reduce follicle count and lower AMH.
3. Genetic and autoimmune factors: Some genetic syndromes and autoimmune attacks on the ovary lead to premature ovarian insufficiency and low AMH.
4. PCOS and follicular arrest: In PCOS, an increased number of small antral follicles produce more AMH, and follicular arrest contributes to persistently elevated AMH.
5. Granulosa cell tumors: Tumoural secretion of AMH causes marked elevations independent of ovarian reserve.
6. Lifestyle and metabolic factors: Obesity, poor nutrition, chronic stress, and metabolic dysregulation can indirectly influence ovarian function and AMH production.

Risk Factors

Several clinical scenarios increase the likelihood of abnormal AMH or make testing particularly useful:

1. Advanced reproductive age: Women over 35 face a higher risk of low AMH and diminished ovarian reserve.
2. Fertility concerns or prior poor IVF response: Patients with repeated poor responses to ovarian stimulation or unexplained infertility benefit from AMH assessment.
3. PCOS features: Irregular cycles, hyperandrogenism, and polycystic ovarian morphology indicate a higher chance of elevated AMH.
4. Prior ovarian surgery or endometriosis: Surgical removal of ovarian tissue or severe endometriosis increases the risk of reduced AMH.
5. Family history of early menopause or known genetic conditions: These raise the index of suspicion for low ovarian reserve.
6. Childhood or developmental anomalies in males: Cryptorchidism, ambiguous genitalia, or disorders of sex development may warrant AMH testing.

Prevention

AMH is a biomarker rather than a disease target, so “prevention” focuses on protecting ovarian reserve, ensuring accurate testing, and avoiding misinterpretation:

1. Early evaluation and counseling: Test AMH when family planning or fertility treatment decisions are considered. Early identification of low AMH permits timely fertility preservation strategies such as cryopreservation.
2. Protect ovarian health: Minimize exposure to gonadotoxic therapies when possible, and consider fertility-sparing options before chemotherapy, radiation, or elective ovarian surgery.
3. Manage conditions that affect AMH: Treat PCOS, control weight and metabolic health, and address autoimmune or endocrine disorders that can harm ovarian function.
4. Lifestyle measures: Maintain balanced nutrition, manage stress, avoid smoking, and limit environmental toxin exposure to support ovarian reserve.
5. Accurate sample handling and validated assays: Use standardized, validated AMH assays and follow proper blood collection/processing procedures to prevent lab variability. Interpret results alongside clinical context rather than as a standalone determinant.
6. Appropriate clinical use: Use AMH to guide stimulation dosing in assisted reproduction, assess ovarian reserve before elective fertility delay, and screen at-risk family members when indicated.
7. Education and shared decision making: Provide patient education about what AMH conveys — it predicts ovarian response and relative reserve but does not guarantee pregnancy — and integrate results into personalized fertility planning.