Thyroid hormone disorder may cause infertility

The thyroid affects fertility

Every tenth Austrian has thyroid problems, especially women. If a woman has an unfulfilled desire to have children, the thyroid values ​​should definitely be examined. Because the small organ below the larynx has a major influence on the fertility of women. In an interview, the hormone and metabolism expert Univ.-Prof. Dr. Thomas Stulnig, which TSH value would be optimal, how best to treat complaints and what the thyroid autoantibodies are all about.

Question: What are the tasks of the thyroid gland in our body?

Stulnig: The main job of the thyroid gland is to produce the thyroid hormones T3 and T4. For this it needs the trace element iodine, which we have to take in from food. Iodine is found in fish or iodized table salt, for example. The thyroid then uses the iodine to produce precisely dosed amounts of hormones that work throughout the body.

The thyroid gland is controlled by the pituitary gland via the hormone TSH (thyroid stimulating hormone; the messenger substance that stimulates the thyroid gland; note), a pea-sized gland that is located in a recess at the base of the brain and controls important parts of our endocrine system

Question: What symptoms can arise in connection with the thyroid gland?

Stulnig: In principle, one must differentiate between functional disorders of the thyroid gland - i.e. over and under function - from nodular formations. These two diseases are among the most common.

There is also inflammation of the thyroid gland. These can be very slow and chronic and then manifest themselves in an underactive thyroid. However, inflammation can also occur relatively quickly and cause severe pain.

Question: Let us come to the dysfunction of the thyroid gland. Which symptoms are typical for underactive or overactive?

Stulnig: The hypothyroidism often shows itself in a few typical symptoms, which, however, only become apparent when the disorder progresses significantly.

But there are also complaints that one would not necessarily assign to the thyroid gland, but are closely related to it. In the case of hypofunction, this can be tiredness, loss of performance, hair loss, cycle irregularities, feeling cold or constipated. In the case of hyperfunction, this could include palpitations, palpitations, increased sweating, loose stools, diarrhea or weight loss.

Question: In order to examine the thyroid gland, the hormone TSH in the blood has to be determined. However, there are different reference ranges. Sometimes an upper limit of the normal value of the TSH of 4 - 4.5 mU / l is given, sometimes even below. There is always talk of lowering the normal limit to 2 - 2.5 mU / l. If you want to have children, the TSH value should be even lower. What is actually true now?

Stulnig: The thyroid is controlled by the hormone TSH, which is produced by the pituitary gland. In this respect, the TSH value is a good anchor of how many thyroid hormones the body needs, since it requests them via the TSH. The exact reference range has been under discussion for a long time.

The upper limit of the reference range is usually 4 mU / l, but the question arises whether TSH values ​​below that would not be more favorable for the patient. There are special situations in which a low TSH value should definitely be aimed for, I am thinking of the desire to have children and pregnancy. Here you should definitely go towards 1.5 mU / l or even below, otherwise I consider values ​​around 2.5 mU / l to be optimal.

Question: Why do the TSH values ​​have to be lower when trying to have children and when pregnant?

Stulnig: The thyroid has a very important influence on fertility. Both overactive and underactive menstrual cycles can cause menstrual disorders, and the monthly period can even be absent. Fertility is then severely restricted or no longer available. Should affected women nevertheless become pregnant, miscarriages occur more frequently, especially in the case of hypofunction.

If the desire to have children remains unfulfilled, the function of the thyroid gland should definitely be clarified. The TSH level is also of great importance during pregnancy. Expectant mothers need more iodine because the need for hormones increases automatically during pregnancy. Even latent hypothyroidism can impair the development of the unborn child.

Question: What does latent hypothyroidism mean?

Stulnig: Latent hypothyroidism is when the TSH level is elevated but the thyroid hormones T3 and T4 are in the normal range. This can also negatively affect the unborn child. Thyroid function should therefore be checked from the start of pregnancy or, even better, before.

Question: In a current meta-analysis (BMJ 2011; 342: d2616) it was found that there is a connection between increased thyroid autoantibodies and an increased number of miscarriages or premature births. What exactly can be thought of as thyroid autoantibodies?

Stulnig: Thyroid autoantibodies are the effects of an immune reaction that are specifically directed against components of the thyroid gland.

Question: And how do these thyroid autoantibodies influence female fertility?

Stulnig: The current meta-analysis showed that there is a clear connection between increased thyroid autoantibodies and an increased rate of miscarriages and premature births. The real mechanism behind this has not yet been clarified and is still under discussion.

One can imagine two reasons: on the one hand, the thyroid could actually be the cause. Raised antibodies can make a somewhat lower thyroid function visible, which means that the thyroid gland has to be driven more in a stressful situation, such as pregnancy, in order to still produce enough thyroid hormones.

The second variant is that the thyroid autoantibodies do not necessarily occur alone, but are part of an immune reaction that is also directed against other parts of the body. Thus, the thyroid auto-antibodies would only be signs of a certain readiness to react on the part of the immune system.

Question: What therapy options are there?

Stulnig: Thyroid hormones can help with the first explanation, that the thyroid is the cause of the increased antibodies. In fact, there are only two smaller studies that have looked at treatment with thyroxine. The rate of miscarriages was therefore reduced.

These studies can currently only be interpreted as an indication that if thyroid auto-antibodies are present, administration of thyroid hormone is beneficial for the course of pregnancy. However, a large randomized, placebo-controlled study on the subject is currently underway.

Question: As part of the mother-child pass examinations, there is no routine examination of the thyroid gland during pregnancy. Why is that?

Stulnig: I would like to see a mandatory examination of the thyroid function as part of the mother-child pass examinations. I advise every woman who wants to become pregnant to have this examination carried out independently. This increases your chances of getting pregnant: even if the woman only suffers from a minimal undersupply and this is then treated accordingly.


Thank you for the interview.

To person: Ao. Univ.-Prof. Dr. Thomas Stulnig is an internist and hormone and metabolism expert. Among other things, he heads the special high blood pressure outpatient clinic and the outpatient clinic for lipid metabolic disorders and congenital metabolic disorders at the Vienna General Hospital.

To the website of ao. Univ.-Prof. Dr. Thomas Stulnig

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