The Anti-Müllerian Hormone (AMH) test is recognized as one of the most crucial and accurate diagnostic tools in fertility medicine and women’s health. This simple blood test provides vital information about a woman’s Ovarian Reserve, which is directly linked to her ability to conceive. Understanding the function and applications of this hormone helps women make more informed decisions regarding family planning and infertility treatments.
What is Anti-Müllerian Hormone (AMH) and how is it produced?
Anti-Müllerian hormone (AMH) is a protein produced primarily in women’s ovaries. This hormone is made in granulosa cells, which surround the small, developing follicles in the ovary. In fact, the highest production of AMH occurs in the preantral and small antral follicles. These follicles, whose number indicates the “reserve” of potential eggs, are the main source of AMH in a woman’s body.
AMH levels remain relatively stable, unlike many other female hormones, such as estradiol or FSH, whose levels constantly fluctuate throughout the menstrual cycle. This stability is a significant advantage, as the test can be performed on any day of the month and does not require specific timing based on the menstrual period.
AMH level is strongly correlated with a woman’s age. Women are born with a fixed number of ovarian follicles, and this number naturally declines with age. Parallel to this natural decrease in follicle count, the AMH level also gradually falls. When the ovarian reserve is nearly depleted and a woman approaches menopause, the AMH level also drops to very low or even zero values.
Assessing Ovarian Reserve: The Most Important Application of AMH
The most critical clinical role of the AMH test is to assess the quantity of the ovarian reserve, which essentially represents the number of remaining and available eggs in a woman’s ovaries.
AMH acts as an “indirect marker” of this reserve:
- High AMH levels usually indicate a higher number of small follicles and, consequently, a high or good ovarian reserve.
- Low AMH levels indicate a decreased ovarian reserve and may suggest a smaller window of time remaining for conception.
It is important to note that AMH only estimates the number of eggs and does not predict their quality. Successful fertility requires a sufficient number of eggs and high-quality eggs, which inevitably decline with increasing age.
Therefore, physicians always interpret AMH results alongside the patient’s age and other clinical findings.
Key Applications of the AMH Test in Medicine
The AMH test has multiple practical applications in various fields of fertility medicine and women’s health.
Predicting Response to Assisted Reproductive Treatments (IVF)
This is perhaps the most crucial application of AMH. In the In Vitro Fertilization (IVF) process, doctors use hormonal medications to stimulate the ovaries to produce multiple eggs simultaneously. The AMH level helps the fertility specialist accurately adjust the dose and type of ovarian stimulation medications:
- If the AMH level is high, the probability of an excellent ovarian response is high, and the doctor may reduce the drug dosage to prevent the complication of Ovarian Hyperstimulation Syndrome (OHSS).
- If the AMH level is low, there is a higher chance of a poor ovarian response, and higher drug dosages or a change in treatment strategy may be needed.
Assessing Fertility Potential and Infertility
The AMH test is often used as a first step in evaluating infertility. This test can provide couples trying to conceive with an overall perspective on the status of the ovaries and the remaining opportunities. Especially for women who plan to delay pregnancy until later ages or who wish to freeze their eggs, AMH provides key information to help determine the appropriate timing for these interventions.
Diagnosing Polycystic Ovary Syndrome (PCOS)
Another important application of AMH is assisting in the diagnosis of Polycystic Ovary Syndrome (PCOS). Women with PCOS often have very high AMH levels. This increase is due to many small follicles (tiny cysts) in the ovaries, each contributing to AMH production. Therefore, AMH can be used as an auxiliary diagnostic tool alongside ultrasound and other hormonal signs.
Predicting Menopause Timing and Diagnosing Premature Menopause
A sharp and early decline in AMH can provide a rough prediction of the time remaining until the onset of menopause. Furthermore, in women who experience Primary Ovarian Insufficiency or Premature Menopause before the age of 40, AMH levels will be distinctly very low or undetectable.
Interpreting AMH Test Results
A specialist must consistently interpret AMH results and take into account the patient’s age and clinical condition. Generally, AMH values are expressed in nanograms per milliliter (ng/mL) and can be categorized into the following ranges:
- High Level (Generally above 4.0 ng/mL): This level may indicate a very good ovarian reserve, but in many cases, it can suggest the possibility of Polycystic Ovary Syndrome (PCOS), which requires further investigation.
- Normal or Optimal Level (Generally between 1.5 and 4.0 ng/mL): This range indicates a healthy and adequate ovarian reserve in reproductive age.
- Low Level (Generally below 1.0 ng/mL): This value indicates a reduced ovarian reserve. In this situation, the physician may recommend accelerating attempts at conception or considering assisted reproductive treatments.
- Very Low Level (Generally below 0.5 ng/mL): This level signifies a severely diminished ovarian reserve, and the likelihood of natural pregnancy will be very low. These values are often observed in older ages or in cases of premature menopause.
Limitations of AMH
Despite the high accuracy of AMH, it is important to be aware of its limitations:
- Egg Quality: AMH provides no information regarding the genetic quality of the eggs. A younger woman with low AMH may have a higher chance of conception than an older woman with a higher AMH because the egg quality of the younger woman is generally better.
- Comprehensive Diagnosis: AMH alone cannot determine fertility potential. For a complete assessment, physicians often combine it with tests like FSH (Follicle-Stimulating Hormone) on the third day of the menstrual cycle and Antral Follicle Count (AFC) via transvaginal ultrasound.
Impact of Genetic Factors on AMH Levels
Genetic factors and age strongly influence the Anti-Müllerian Hormone (AMH) level and, consequently, a woman’s ovarian reserve. Certain chromosomal disorders and gene mutations can cause an early decline in ovarian reserve.
For instance, conditions like Turner Syndrome or abnormalities related to the X chromosome can lead to a severe and early decrease in AMH and result in Premature Ovarian Insufficiency (POI).
Furthermore, polymorphisms (or natural variations) in the genes that affect the production, regulation, or metabolism of AMH can cause the baseline AMH level to differ among individuals, regardless of age.
Therefore, some women are genetically born with a lower initial ovarian reserve, which results in low AMH levels at a younger age and requires more active fertility management.
The Role of Autoimmune Diseases in Diminished Ovarian Reserve
Autoimmune diseases are another significant cause of diminished ovarian reserve and low AMH levels, particularly observed in cases of Premature Ovarian Insufficiency (POI).
Under these conditions, the body’s immune system mistakenly attacks its healthy tissues. When this attack targets the ovarian tissue (the AMH-producing cells), a chronic inflammatory reaction damages or destroys the ovarian follicles prematurely.
Diseases such as Hashimoto’s thyroiditis, lupus, and certain adrenal gland disorders are associated with an increased risk of diminished ovarian reserve. The resulting inflammation can disrupt the hormonal function of the ovaries, directly causing a decrease in follicle count and a drop in AMH hormone levels.
Impact of Key Environmental and Lifestyle Factors on AMH Levels
Smoking and Toxic Substances
Smoking, whether active or passive, is one of the strongest external factors detrimental to ovarian reserve. Toxic substances found in tobacco smoke, such as nicotine and aromatic hydrocarbons, can directly damage the DNA of follicular cells.
This damage accelerates the depletion of eggs, resulting in a noticeable decrease in AMH levels in smoking women compared to non-smoking women of the same age. This factor can also lower the age of menopause.
Medications and Surgery
Two important medical factors that affect AMH are hormonal medications and ovarian surgeries:
- Oral Contraceptive Pills (OCPs): These pills can temporarily decrease the level of AMH in the blood. This reduction does not reflect the true ovarian reserve but results from the temporary suppression of follicular activity. After discontinuing OCP use, AMH levels typically return to their normal state.
- Ovarian Surgery: Any surgery that involves manipulating or removing ovarian tissue (especially surgery for endometriosis cysts or endometriomas) can unintentionally damage the surrounding healthy tissue. This physical damage to the AMH-producing follicles leads to a permanent reduction in ovarian reserve and, consequently, a drop in the AMH level.
Obesity and Body Weight
Body weight has a complex effect on AMH, often mediated through underlying hormonal disorders:
- Obesity and Insulin Resistance: Excess weight can lead to insulin resistance and increased production of male hormones (androgens). This condition disrupts the hormonal balance and affects the ovulation cycle.
- Changes in Results: Some studies have shown that AMH levels may be lower in obese women, particularly those without polycystic ovary syndrome (PCOS), compared to those of women of normal weight. However, it should be noted that obesity and excess weight primarily affect the quality of ovulation rather than merely the egg count.
The bottom line
The Anti-Müllerian Hormone (AMH) test is a powerful and vital diagnostic tool that assesses a woman’s ovarian status. This test helps women understand their “biological clock” for conception and make important decisions regarding the timing of pregnancy attempts, egg freezing, or selecting the appropriate course for infertility treatment.
It is always recommended that the results of this test be interpreted by a Fertility Specialist or Obstetrician/Gynecologist to develop a personalized and effective treatment plan. Dr. Arjang Naim can accompany you on this journey.
Additional questions
- Can the AMH level predict when a woman will reach menopause?
The gradual decline in AMH can be an approximate marker to estimate the time remaining until menopause. While the test does not provide a precise date, a rapid and significant decrease in AMH over a period of time may suggest the possibility of early or premature menopause. However, it must always be interpreted with the woman’s age and other clinical findings.
- If a woman undergoes chemotherapy or radiation therapy for cancer treatment, what effect will this have on her AMH level?
Chemotherapy and radiation therapy, especially treatments that target the pelvis, often damage the follicular cells that produce AMH. These treatments can cause a sudden and severe drop in AMH, leading to a diminished ovarian reserve or even Premature Ovarian Insufficiency (POI).
- Why do AMH levels decrease during pregnancy, and does this indicate a diminished ovarian reserve?
During pregnancy, AMH production by the follicles is suppressed due to the high levels of other hormones, particularly progesterone and estrogen. This is a temporary decrease and is not a sign of permanent diminished ovarian reserve. AMH levels typically return to their normal (pre-pregnancy) state after childbirth and breastfeeding.
- Do simple ovarian cysts (other than endometrioma cysts) affect the AMH test results?
Simple or functional cysts, which often develop during a normal monthly cycle, usually do not significantly impact the overall AMH level. However, endometrioma cysts (caused by endometriosis) or surgery to remove them often lead to a permanent reduction in AMH levels.
- Does a decrease in AMH level indicate lower egg quality?
No, AMH only indicates the number (quantity) of eggs, not their quality. However, because the decrease in AMH naturally occurs with increasing age, and egg quality also declines, these two factors often run parallel to one another.
References
https://my.clevelandclinic.org/health/diagnostics/22681-anti-mullerian-hormone-test
https://www.medparkhospital.com/en-US/disease-and-treatment/anti-mullerian-hormone-test
https://www.ivf.com.au/planning-for-pregnancy/female-fertility/ovarian-reserve-amh-test
https://www.fertilityassociates.co.nz/anti-mullerian-hormone-amh-fertility-test
https://www.advancedfertility.com/infertility-testing/amh-fertility-testing
https://monashivf.com/services/early-intervention/amh-blood-test/