“Think about the thyroid gland during pregnancy,” reminds awareness campaign

Thyroid under increased pressure

Pregnancy generally places higher demands on the thyroid gland – the production of thyroxine must increase by approximately half. A healthy thyroid gland, assuming it has sufficient iodine intake, will respond correctly to these increased demands during pregnancy. On the other hand, an organ displaying functional disorders, even if only subclinical up to that point, might not be able to meet the need for thyroid hormones, which increases very quickly.

Hormones produced by the thyroid gland are very important already in the first trimester, the first 3 months of fetal development, during the formation of the nervous system. Hypothyroidism during this period can lead to irreversible disruptions of healthy development. So-called cretinism is rare nowadays and in our conditions, but the impact of maternal thyroid function during pregnancy on further neuropsychological characteristics of the individual, such as the risk of autism or ADHD, is still being studied. Deviations in thyroid function can also cause infertility or miscarriages, as well as health complications for both the fetus and the mother in later stages of pregnancy. For example, the risk of premature birth increases.

Symptoms may remain unnoticed

Decreased thyroid activity does not typically have as alarming symptoms as hyperthyroidism. It manifests as fatigue, cold intolerance, swelling, shortness of breath, apathy, and constipation, sometimes joint pain. Pregnant women can easily mistake these symptoms for normal changes associated with their condition. The only way to safely verify proper thyroid function in this situation is through laboratory testing. It can be said that at least checking TSH is now considered good practice in the care of a pregnant patient in a gynecological office. However, this is not yet “officially endorsed” screening – a program to verify the benefits of implementing screening in Czech conditions is being prepared, and its results will be known no earlier than the end of 2022.

Therapy must begin immediately

Hypothyroidism in pregnant women requires attention in both its subclinical and manifest forms. Its treatment is usually the domain of an endocrinologist, but any physician who detects the problem can initiate substitution therapy with thyroxine at full dose, usually in the range of 50–100 µg/day, and refer the treated patient for further endocrinological examination.

In women with known and treated hypothyroidism, it is necessary to increase the substitution dose of thyroxine by half from the beginning of pregnancy and to monitor TSH levels (which should not rise above 2.5 mIU/l in the first trimester) and free thyroxine (fT4) every 4–6 weeks. In the case of subclinical hypothyroidism, treatment should ideally begin preconception, but no later than when pregnancy is confirmed.

Subclinical hyperthyroidism (TSH suppression) does not require treatment but may deserve closer monitoring. Clinically manifest hyperthyroidism must be treated with antithyroid drugs and, in special cases, thyroidectomy, while radioiodine therapy is contraindicated. A pregnant woman with thyrotoxicosis should always be under the care of an experienced endocrinologist.

(luko)

Sources:
1. Zamrazil V. Thyroid gland and pregnancy. Internal Medicine 2010; 12 (4): 191–195.
2. Komendová I., Špitálníková S., Horáček J. Intellectual performance of children of mothers with thyroid disorders during pregnancy (preliminary research results). Postgraduate Medicine 2014; 16 (5): 556–562.
3. Límanová Z., Jiskra J., Moravčíková D., Karen I. Diagnosis and treatment of thyroid disorders. Update 2015. Recommended diagnostic and therapeutic procedures for VPL. Center for Recommended Procedures for General Practitioners, Society of General Practice CLS JEP, 2015.
4. Jiskra J., Límanová Z. Recommendations for prevention, early detection, and treatment of thyroid disorders during pregnancy 2018. Czech Endocrinological Society CLS JEP, 2018.