"In our opinion, in many cases, proper treatment allows to get pregnant in a short time in women with thyroid dysfunction" - says Prof. Małgorzata Karbownik-Lewińska from the Department of Endocrinology and Metabolic Diseases at the Polish Mother`s Memorial Hospital Research Institute in Łódź, who specialises oxidative stress research.

Oxidative stress is a situation, in which more free radicals (and other reactive oxygen species) are formed in our body than our natural defence mechanisms, such as enzymes and antioxidants, are able to neutralize.

"Free radicals destroy biological structures, but under physiological conditions - that is, in conditions of full health - a certain level of them is necessary, the more so that the reactions related to oxidative stress are necessary for many physiological processes, such as the synthesis of thyroid hormones" - explains the expert from the Polish Mother`s Memorial Hospital Research Institute in Łódź.

She emphasises that pathological phenomena only occur when the level of oxidative stress is higher. Prolonged oxidative stress may be the cause of neoplastic diseases, type 2 diabetes or neurodegenerative diseases.

Specialists from the Department of Endocrinology and Metabolic Diseases at the Polish Mother`s Memorial Hospital Research Institute conducted a study to show the relationship between the abnormal TSH level in women of childbearing age and oxidative stress.

TSH (thyroid-stimulating hormone) is produced by the pituitary gland. It stimulates the thyroid to synthesise and secrete hormones (thyroxine - T4 and triiodothyronine - T3), which, in turn, stimulate the metabolic processes. Changes in the level of TSH in the blood may indicate both early-stage (and therefore minor) and severe thyroid disorder; the level of TSH is the first to change in a patient with an early-stage thyroid dysfunction. Too low levels of TSH may indicate hyperthyroidism, and too high levels - hypothyroidism.

The research was carried out on seemingly healthy women of childbearing age. In their case, the levels of thyroid hormones and TSH index were within the limits of reference values (from about 0.5 to 4.5 mIU/l). Seemingly healthy, because - as Prof. Karbownik-Lewińska emphasises - it is known that in relatively young people TSH level should not exceed 2.5 mIU/l, which is in the lower range of reference values.

This is the reason for the debate in the scientific world whether patients of childbearing age, and in particular those who are already pregnant or are planning pregnancy - in whom the TSH index is higher, but still within the norm - should be treated similarly to people with diagnosed hypothyroidism.

In the study conducted by specialists from the Polish Mother`s Memorial Hospital Research Institute, women of childbearing age, although not yet pregnant, in whom the TSH index was in the upper range of reference values (above 2.5 mIU/l), were more likely to have abnormal lipid profile values. It is well known that an abnormal lipid profile is associated with an increased risk of atherosclerosis and cardiovascular disease.

The same patients also had an increased level of oxidative damage to the cell membrane lipids (lipid peroxidation), which is an indicator of oxidative stress.

"In our opinion, patients with such results should be under very careful observation, and in most cases they should be treated" - emphasises Prof. Karbownik-Lewińska.

It is known that higher levels of TSH are associated with lower likelihood of conception. Therefore - taking into account the results of research conducted in Łódź, it can be assumed that oxidative stress impedes fertilization in some way, or at least is one of the mechanisms of infertility in patients with thyroid dysfunction, the researcher suggests.

"If these patients are treated properly with left-handed thyroxine (like patients with diagnosed hypothyroidism), TSH will be lowered and oxidative stress will probably also be reduced. I think that in this mechanism, becoming pregnant will be more likely. The fact that patients with lower TSH values are more likely to get pregnant, is already documented" - the expert says.

Demonstrating the influence of minor thyroid dysfunctions on oxidative stress, and thus on problems related to pregnancy, will require many years of research. But the daily practice of doctors from the Department of Endocrinology and Metabolic Diseases appears to confirm it.

"It is clear from our daily medical practice that in many patients with sub-optimal thyroid function results, who have not been able to get pregnant for a long time, after recognizing thyroid dysfunction and introducing the proper treatment, in the majority of cases fertilization occurs in a short time" - concludes Prof. Małgorzata Karbownik-Lewińska.

PAP - Science in Poland, Kamil Szubański

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