AMH and FSH tests: How does it work?

Anti-Müller hormone (AMH) and follicle-stimulating hormone (FSH) are two hormones closely involved in the growth and development of eggs. The ovum is stored in the ovary (ovary). They are safely packed in so-called follicles.

A number of follicles is constantly stimulated to develop so that the egg can prepare for fertilization. An unhealthy diet and lifestyle can influence the development of these follicles and the level of fertility. Measuring AMH and FSH gives an overview of the quantity and quality of follicles.

AMH: What is its function in the body ?

The development of the gonads is the same during the first six weeks, so there is no external difference between a male and a female embryo. The internal and external genitals are always the same. In the lower abdomen are the precursors of the primordial gonads and two double-sided tubes, the Müllerse tube and the Wolffse tube. The primordial gonads develop into testes or ovaries.

The Mullerian tube only grows in the female embryo and the Wolff tube only in the male embryo. In male embryos, very large amounts of anti-Müller hormone (AMH) are produced in week 6, so that the Müller’s tube does not develop further. Even after birth, the AMH concentration in serum in boys is still very high.

AMH is produced in women of childbearing age by small vesicles of growing eggs (follicles) in the ovary (ovary). At a certain stage of follicle growth, a small, fluid-filled cavity (lair) forms, called antral follicles. When these follicles are 2 to 7 mm in size, the number of granulosa cells in the follicles increases and they process a lot of AMH. Of all the follicles present with a size of 8 to 12 mm, one is chosen to become a large preovulatory follicle, the rest is broken down.

This process of growth and selection of the dominant follicle is determined by the presence of sufficient FSH, a hormone produced in the pituitary gland. But at the same time, the antral follicles also produce estradiol, which inhibits the release of FSH into the pituitary gland. The follicle that absorbed the most FSH in a short time and grew the hardest won. The egg in this follicle is more mature and is released when the follicle bursts (ovulation or ovulation).

This last selection and maturation process takes 14 days (first part of the menstrual cycle). The time of ovulation is determined by a sharp increase in the other pituitary hormones, LH.

Certain resting (primordial) follicles are continuously stimulated to develop. If there is enough (or too much) AMH, this growth impulse is actually inhibited by AMH (negative feedback) and is again stimulated when the level of AMH drops. The more antral follicles, the higher the AMH content.

There is a very good correlation between the number of growing follicles in the ovaries and the level of AMH in the blood. A minimum number of growing follicles of about 15 must be present for a good pregnancy rate corresponding to an AMH value of at least 0.7 µg / l. AMH is highest in young women aged 13 to 30. With age, the level of AMH gradually drops to a post-menopausal value of zero.

Obviously, good ovulation is highly dependent on the dynamics of estradiol, LH, FSH and AMH. It seems that lifestyle and diet can contribute to an optimal ovulation cycle.

What are the values found in the body?

Menopause prediction (early)

On average, a woman enters menopause at 50, with a difference of 10 years. We speak of premature insufficiency (POF) when menopause occurs before the 40th year. A very low AMH (<0.07 µg / l) means that there are no or very few growing follicles and corresponds to menopause. Menopause can be definitively diagnosed if it has not been there for a year after the last menstrual period; it can therefore only be determined afterwards. AMH and FSH tests can tell in advance if an irregular or missing cycle signals the start of menopause. The combination of a decrease in AMH and an increase in FSH is a fairly strong predictor.

Until the age of 30, AMH is highest in the blood. After that, it decreases gradually, for most women, from about 0.15 µg / l per year to 45 years, then the decrease is slightly less rapid. Calculation models have been created that allow us to estimate the time when menopause will occur. In women under 30 and high / normal AMH values, this prediction is too inaccurate; accuracy increases with age and lower AMH values. For example, if a woman at 25 has an AMH value of 1.5 µg / l, it does not make sense to wait another 10 years to get pregnant. There is a good chance that AMH will fall below 0.7 µg / l, which is a limit value at which the risk of spontaneous pregnancy greatly decreases.

The combination of AMH and FSH is therefore very useful for obtaining an indication of the follicular stock and for estimating when menopause may occur. Both tests are also useful when there are doubts about delaying a pregnancy to be ahead of the POF. It is also important to realize that an optimal AMH value is a condition, but does not guarantee pregnancy. Fertility depends on much more than a good supply of growing follicles. AMH cannot therefore be used as a measure of fertility and for a probability of pregnancy. Women undergoing treatment at a fertility clinic have an average AMH value comparable to that of fertile women of the same age. But the average age is relatively high.

AMH and FSH in polycystic ovary syndrome (PCOS)

The mention “more is better” does not apply to AMH. There are situations where many antral follicles are ready, but the maturation of the eggs and the growth of the follicles do not go well. The follicles grow, but do not mature properly. Cystic follicles can therefore develop. If these follicles increase in size and number and there are specific complaints and symptoms, we are talking about polycystic ovary syndrome (PCOS). This is accompanied by an increase in AMH values, but a reduced probability of pregnancy. The risk of PCOS increases if the AMH value is higher than the upper age limit. Studies also indicate that an AMH value greater than 5 µg / l already indicates an increased risk of PCOS (or at its initial stage).

FSH is highly dependent on the cycle and can only be interpreted correctly if the blood sample is taken on days 2 to 5 after the first day of menstruation (start of a new cycle), preferably on day 3. In women who have little or no irregular rules the simultaneous determination of AMH and FSH is necessary for a correct interpretation. On the third day of the cycle, the level of estradiol in the blood is stable and low, which gives a basal FSH value between 3 and 10 U / l.

Functional hypothalamic amenorrhea

Another reason for lack of menstruation for more than 6 months (amenorrhea) may lie in a negative energy balance, which may or may not be associated with active sport and / or an acute psychological stressor. The hypothalamus is suppressed so that there is little or no secretion of GnRH. This is helpful for the body to conserve energy for vital functions. Hence the term functional hypothalamic ammenoroe.

The release of FSH and LH is lower than in women of normal cycle of comparable age. However, the serum AMH values ​​are not decreased. These are normal and, in some cases, even high. When AMH increases in these women, it is very similar to PCOS (but with a lower FSH value) and often also with an increased number of follicles.

There is a slightly higher risk of developing PCOS later. When stress triggers (negative energy balance, overwork, psychological stress) are reduced, the menstrual cycle returns to normal.

How should we interpret the values?

The level of AMH in serum / plasma has a fairly large intra-individual distribution, depending on the number of groin follicles (see above). Reference values ​​are always declared by us according to age and sex (this does not apply to all laboratories). For a 19 year old woman, it is from 0.8 to 8.0 µg / l and for a 40 year old woman, it is from 0.1 to 4.0 µg / l. We apply an optimal AMH value of 0.7 to 5.0 µg / l for all ages. When the AMH falls below 0.7 µg / l, fertility decreases and when the AMH falls below 0.07 µg / l, this is called biological menopause.

We talk about premature ovarian failure at menopause before the age of 40. This can already be predicted 10 years earlier on the basis of levels of AMH that are too low for age, given an average decrease of 0.15 µg / l per year.

In women with oligo- or ammenoreu and AMH values ​​greater than 5.0 µg / l (in young women greater than 8.0 µg / l) and low / normal FSH (3 – 8 U / l), the risk of PCOS increases (especially if it also exceeds the reference limit depending on age) and the risk of pregnancy decreases.

In women with ammenoroe and normal AMH values ​​for age, but with reduced FSH values ​​(<3 U / l), there is a high risk of functional hypothalamic ammenoroe caused by a negative long-term energy balance, possibly combined to excessive sports and / or psychological stress.