What are additional causes of elevated anti‑Müllerian hormone (AMH) in a 36‑year‑old woman besides polycystic ovary syndrome (PCOS)?

Additional Causes of Elevated AMH Beyond PCOS

While PCOS is the most common cause of elevated AMH, other important conditions to consider include granulosa cell tumors, functional hypothalamic amenorrhea with polycystic ovarian morphology, hypogonadotropic hypogonadism, and physiologically enlarged or supernumerary ovaries.

Key Differential Diagnoses

Granulosa Cell Tumors (GCTs)

• GCTs are a critical diagnosis not to miss, as they represent malignant pathology that can present with markedly elevated AMH levels 1
• These tumors produce AMH from neoplastic granulosa cells
• Clinical pearl: Consider GCTs in the differential diagnosis of chronic anovulation even when ovarian steroid production appears normal, particularly if AMH levels are unusually high for the patient's age 1
• GCTs may present with pronounced AMH and LH elevation but paradoxically normal steroid levels, supporting AMH's role in neuroendocrine dysfunction 1

Functional Hypothalamic Amenorrhea (FHA) with PCOM

• Approximately 30% of women in the general population have polycystic ovarian morphology on ultrasound, making this finding non-specific 2
• Women with FHA can present with PCOM, creating diagnostic confusion when amenorrhea and PCOM coexist 2
• The combination of amenorrhea and PCOM does not automatically indicate PCOS—you must distinguish between FHA with incidental PCOM versus true PCOS
• FHA patients typically lack the hyperandrogenism seen in PCOS

Hypogonadotropic Hypogonadism

• AMH serves as an important diagnostic marker in women with hypogonadotropic hypogonadism 1
• These patients may have elevated AMH due to accumulated small antral follicles that are not being recruited due to insufficient gonadotropin stimulation
• Pituitary dysfunction combined with PCOS can create diagnostic challenges 1

Unusually Enlarged or Supernumerary Ovaries

• Increased ovarian volume alone can produce elevated AMH levels 1
• It remains unclear whether increased AMH from enlarged ovaries represents actual PCOS or a distinct subgroup requiring separate classification 1
• These cases challenge current diagnostic frameworks

Physiologic Considerations

Age-Related Variation

• AMH naturally varies with age, and this relationship differs between healthy women and those with PCOS 3
• Age explains nearly 40% of AMH variation in healthy women but only 20% in women with PCOS 3
• In your 36-year-old patient, age-specific reference ranges are essential for proper interpretation

Technical and Assay Factors

• AMH assays display differential responses to pre-analytical proteolysis, conformational changes, and interfering substances 4
• Sample-to-sample variability and between-assay conversion discrepancies can falsely elevate results 4
• Ensure proper sample handling and use standardized assays when interpreting elevated AMH

Diagnostic Approach

When encountering elevated AMH in a 36-year-old woman:

1. Rule out malignancy first: Obtain pelvic ultrasound to exclude granulosa cell tumors, especially if AMH is markedly elevated for age
2. Assess for PCOS criteria: Evaluate for oligo/anovulation and hyperandrogenism (clinical or biochemical)
3. Consider FHA: Look for low gonadotropins, history of excessive exercise, low body weight, or stress
4. Evaluate pituitary function: Check FSH, LH, prolactin, and thyroid function to exclude hypogonadotropic hypogonadism
5. Document ovarian morphology carefully: Note ovarian volume and follicle distribution pattern

Critical Pitfalls to Avoid

• Do not diagnose PCOS based on elevated AMH alone—international guidelines explicitly state that AMH should not be used as a single test for PCOS diagnosis 4
• Do not assume all amenorrhea with PCOM equals PCOS—FHA with incidental PCOM is a distinct entity 2
• Do not overlook GCTs in chronic anovulation—even with normal steroids, unusually high AMH warrants imaging 1
• Remember that AMH elevation in isolation, without meeting other Rotterdam criteria, does not establish PCOS diagnosis

The heterogeneity of PCOS and overlap with other conditions producing elevated AMH emphasizes the need for comprehensive evaluation rather than relying on AMH as a standalone marker 1.