AMH Test: Principle, Procedure, and Clinical Significance

The Anti-Müllerian Hormone (AMH) test is an important diagnostic measurement in reproductive medicine, providing a cycle-independent measure of ovarian reserve, fertility potential, and endocrine health. Its stability (CV <5%) and strong correlation with antral follicle count (r=0.8–0.9) make it a preferred biomarker over FSH or estradiol for fertility assessment, PCOS diagnosis, and menopause prediction. This article explores the AMH test’s biochemical foundation, testing methods, clinical indications, and limitations, offering a detailed resource for clinicians and laboratory professionals.

What is AMH? Understanding the Hormone Behind Fertility Testing

AMH is a 140-kDa homodimeric glycoprotein in the TGF-β superfamily, critical for reproductive development. In females, granulosa cells of pre-antral and small antral follicles secrete AMH, reflecting the non-growing follicle pool. In males, Sertoli cells produce AMH during fetal life, inhibiting Müllerian duct formation via AMHR2 receptor signaling and SMAD1/5/8 pathways. AMH’s diagnostic utility lies in its minimal menstrual cycle variability, enabling applications in:

• Ovarian reserve assessment
• IVF response prediction
• PCOS diagnosis
• Menopause timeline estimation
• Gonadotoxicity monitoring post-chemotherapy

AMH levels decline with age:

Age Group	AMH Range (ng/mL)
25–29	2.5–4.5
30–34	2.0–3.5
35–39	1.5–3.0
40+	<1.0
Postmenopausal	Undetectable

Interpretation must account for assay type and patient-specific factors like ethnicity or comorbidities.

When and Why Should You Get an AMH Test?

The AMH test is indicated in specific clinical scenarios to guide reproductive and endocrine management:

• Fertility Assessment: Recommended for women planning pregnancy, especially those over 30 or with irregular cycles, to evaluate ovarian reserve and fertility potential.
• IVF Planning: Essential for predicting ovarian response to stimulation, helping tailor gonadotropin dosing and reduce risks like ovarian hyperstimulation syndrome (OHSS).
• PCOS Evaluation: Indicated for women with symptoms like irregular periods or hirsutism, as elevated AMH supports Rotterdam diagnostic criteria.
• Menopause Prediction: Useful for women in their late 30s or early 40s with menopausal symptoms to estimate reproductive lifespan.
• Oncology Patients: Advised before or after gonadotoxic treatments (e.g., chemotherapy) to assess fertility preservation options.
• Delayed Childbearing: Suggested for women considering egg freezing to quantify ovarian reserve and inform timing.
• Unexplained Infertility: Helps identify low ovarian reserve in couples with no clear cause of infertility after initial workup.

Note: AMH testing is not routinely recommended for healthy women under 25 with no fertility concerns, as levels are typically high and less predictive.

AMH Test Sample Collection: Guidelines and Best Practices

One of the key advantages of the AMH test is its cycle independence — AMH levels remain relatively stable throughout the menstrual cycle. Therefore, blood samples for AMH measurement can be collected at any time, including during menstruation or other phases of the cycle.

Some recent studies suggest there may be minor fluctuations during follicular phases, but these are usually within assay variability and not clinically significant for most patients. For increased consistency, some clinicians prefer testing in the early follicular phase (days 2–5), but this is optional.

Specimen Type

• Preferred: Serum collected in plain tubes
• Acceptable: Plasma collected in EDTA or heparin tubes

Sample Handling and Stability

• Room temperature: Stable up to 24 hours
• Refrigerated (2–8°C): Stable up to 72 hours
• Frozen (−20°C or lower): Stable for several months

Pre-Analytical Considerations

• Avoid hemolysis or lipemia, which can interfere with test accuracy
• Process samples immediate —serum separation within 2 hours of collection
• Minimize freeze-thaw cycles to prevent degradation

Following these protocols is critical for ensuring reliable AMH results essential for clinical decision-making.

How is the AMH Test Performed? From ELISA to Digital Platforms

AMH assays vary in sensitivity, automation, and cost:

Method	Sensitivity (ng/mL)	CV (%)	Automation	Cost
ELISA	0.1	5–10	Low	Low
CLIA	0.01	2–5	High	Medium
Digital & High-Sensitivity	<0.001	<2	High	High

Emerging technologies include microfluidic devices for point-of-care testing and AI models integrating AMH with AFC/FSH for IVF outcome prediction. Inter-laboratory variations is also common due to technical standarizations and the equiment used.

Interpreting AMH Results:

The interpretation of AMH levels must be made based on age, medical history, and the reason for testing. Here’s how to make sense of AMH results:

1. High AMH Levels (>4.5 ng/mL)

• What it means: High AMH levels typically reflect a greater number of antral follicles, indicating a strong ovarian reserve. This is generally considered favorable in fertility assessments.
• Clinical implications:
  • May suggest polycystic ovary syndrome (PCOS), especially when accompanied by other symptoms like irregular cycles or excessive androgens.
  • In women undergoing IVF, high AMH levels can increase the risk of ovarian hyperstimulation syndrome (OHSS), a potentially serious response to fertility medications.
• Further evaluation may be required to rule out PCOS or to work on fertility treatments accordingly.

2. Normal AMH Levels (1.0–4.5 ng/mL)

• What it means: AMH levels within this range usually suggest a healthy ovarian reserve and are considered normal for most reproductive-age women.
• Clinical implications:
  • Indicates a balanced likelihood of natural conception or favorable response to fertility treatments.
  • Monitoring of AMH levels may be recommended in cases involving irregular cycles, infertility, or advanced maternal age.

3. Low AMH Levels (<1.0 ng/mL)

• What it means: Low levels of AMH typically reflect a diminished ovarian reserve, which may impact fertility potential.
• Clinical implications:
  • May signal perimenopause or primary ovarian insufficiency (POI), especially in women under 40.
  • Suggests fewer remaining eggs, possibly affecting natural conception chances and IVF response.
  • Not a definitive marker of infertility, but a prompt for timely fertility counseling or preservation options like egg freezing.
• Common symptoms:
  • Difficulty conceiving
  • Irregular or shortened menstrual cycles
  • Early menopause signs (e.g., hot flashes, mood changes)

Factors That May Influence AMH Levels

Several variables can affect AMH levels, and these should be considered during interpretation:

• Age: Naturally declines with age; AMH is highest in early adulthood and decreases steadily over time.
• Vitamin D levels: Deficiency may lower AMH production; supplementation can sometimes improve readings.
• Smoking: Associated with reduced AMH and accelerated ovarian aging.
• Hormonal contraceptives: Can temporarily suppress AMH levels, though ovarian reserve itself is unaffected.
• Assay variation: Different labs or test kits may yield slightly different results; it’s best to interpret AMH trends over time using the same testing method.

Cycle Timing and AMH Stability

AMH is relatively stable across the menstrual cycle, unlike hormones such as FSH or LH. Minor daily fluctuations may occur, but these are usually within the assay’s margin of error and do not significantly affect clinical interpretation.

Frequently Asked Questions (FAQs)

Q: Does the menstrual cycle phase affect AMH levels or testing?
A: AMH is largely independent of menstrual cycle timing, allowing blood to be drawn at any time. Minor fluctuations may occur but are clinically insignificant.

Q: Can high AMH guarantee fertility?
A: No, AMH indicates egg quantity but not egg quality.

Q: How consistent are AMH lab results?
A: Consistency depends on assay standardization; CLIA or digital assays offer higher precision.

Q: Do lifestyle factors impact AMH?
A: Yes, smoking, obesity, and low vitamin D may affect levels.

Q: Is AMH reliable for PCOS diagnosis?
A: It supports diagnosis but should be used alongside other clinical criteria.

Q: What is the best AMH assay?
A: CLIA and digital high-sensitivity assays provide superior accuracy and precision.

Conclusion

The AMH test is essential in reproductive medicine, guiding fertility planning, PCOS diagnosis, and menopause management. Advanced assay technologies combined with rigorous lab practices empower clinicians to deliver precise, patient-centered care. Ongoing standardization and technological innovations will further enhance the test’s clinical utility.

References

• La Marca A, Volpe A. Clin Endocrinol (Oxf). 2006;64(6):603–610. doi:10.1111/j.1365-2265.2006.02590.x
• Broer SL, et al. Hum Reprod Update. 2014;20(5):688–701. doi:10.1093/humupd/dmu020
• Kelsey TW, et al. PLoS One. 2011;6(7):e22024. doi:10.1371/journal.pone.0022024
• Iliodromiti S, et al. J Clin Endocrinol Metab. 2013;98(8):3332–3340. doi:10.1210/jc.2013-1393
• Mayo Clinic Staff. “Anti-Müllerian Hormone (AMH) Test.” Mayo Clinic. https://www.mayoclinic.org/tests-procedures/amh-test/about/pac-20385028