Is a decreased Anti-Mullerian Hormone (AMH) level, irregular or absent menstrual cycles, and polycystic ovarian morphology diagnostic of Polycystic Ovary Syndrome (PCOS)?

AMH Alone Cannot Diagnose PCOS

Your AMH levels of 45 pmol/L (current) and 71 pmol/L (one year ago), combined with irregular/absent cycles and polycystic ovarian morphology on ultrasound, strongly suggest PCOS and meet the Rotterdam diagnostic criteria—but AMH itself is not currently an accepted diagnostic criterion. You meet the diagnosis through the combination of irregular cycles (ovulatory dysfunction) and polycystic ovarian morphology, which are two of the three Rotterdam criteria needed 1.

Why AMH Is Not Used for Diagnosis

AMH cannot replace established diagnostic criteria despite being elevated in PCOS. Current international guidelines explicitly recommend against using AMH for PCOS diagnosis due to several critical limitations 2, 1:

• Lack of standardization: Different AMH assays produce inconsistent results, and there is no international reference standard, making direct comparison between laboratories problematic 2, 3
• No validated cut-offs: While research suggests cut-offs around 20 pmol/L in adults 4 or 6-7 ng/mL (approximately 43-50 pmol/L) in adolescents 5, these are not clinically validated for diagnostic use 2, 1
• Significant overlap: AMH levels overlap considerably between women with and without PCOS, particularly in younger women, resulting in poor diagnostic specificity 2, 3
• Age-dependent variability: AMH levels are naturally high in adolescence and decline with age, requiring age-specific reference ranges that don't yet exist 2

Your Diagnosis Based on Rotterdam Criteria

You meet PCOS diagnostic criteria through two of the three required features 1, 6:

1. Ovulatory dysfunction: Irregular or absent menstrual cycles (cycle length >35 days indicates chronic anovulation) 1
2. Polycystic ovarian morphology: Confirmed on ultrasound (≥20 follicles per ovary of 2-9mm diameter, or ovarian volume >10 mL using transvaginal ultrasound with ≥8 MHz transducer) 1

The third criterion—hyperandrogenism (clinical signs like hirsutism, acne, or biochemical elevation of androgens)—is not required if you have the other two 1, 6.

Important Diagnostic Considerations

Before confirming PCOS, other conditions must be excluded 1, 7:

• Thyroid disease and prolactin disorders 1
• Non-classic congenital adrenal hyperplasia 1
• Cushing's syndrome 1
• Androgen-secreting tumors (characterized by rapid onset and severe hyperandrogenism) 1

If you are taking hormonal contraception (including progestin-only implants like Implanon), hormone testing becomes unreliable and should be performed after discontinuation or expiration of the contraceptive 1.

Understanding Your AMH Levels

While not diagnostic, your AMH levels provide context:

• Your current AMH of 45 pmol/L is elevated compared to women without PCOS (typical mean ~13 pmol/L in women with normal ovaries) 8
• The decline from 71 to 45 pmol/L over one year is notable but doesn't change the diagnosis, as AMH naturally fluctuates and declines with age 2, 3
• Higher AMH correlates with more severe PCOS phenotypes: Women with all three Rotterdam features (polycystic ovaries, hyperandrogenism, and ovulatory dysfunction) have the highest AMH levels (mean 72.7 pmol/L) 8

Critical Pitfall to Avoid

Up to one-third of reproductive-aged women without PCOS have polycystic ovarian morphology on ultrasound 1. This is why ultrasound findings alone are insufficient—you must have at least one other Rotterdam criterion (which you do: irregular cycles) 1, 6. Additionally, ultrasound should not be used for diagnosis in adolescents within 8 years of menarche due to high false-positive rates from normal multifollicular ovaries 2, 1.

Next Steps

Confirm the diagnosis requires 1:

• Documenting menstrual history with cycle length >35 days 1
• Assessing for clinical hyperandrogenism (hirsutism, acne, male-pattern balding) 1
• Biochemical testing if not already done: total testosterone via LC-MS/MS (74% sensitivity, 86% specificity) or calculated free testosterone (89% sensitivity, 83% specificity) 1
• Excluding differential diagnoses listed above 1
• Metabolic screening: All women with PCOS should be screened for type 2 diabetes, glucose intolerance, and dyslipidemia 1