The use of L-thyroxine in the treatment of thyroid pathologies and problems of therapy control (literature review)

Abstract

Background. Thyroid disease is one of the most common pathologies in the world, wich includs hypothyroidism, hyperthyroidism and thyroid cancer. At the present, there is an increase in their cases. The thyroid gland is an extremely important for the health of a person, thyroid hormones are necessary for the normal functioning of all tissues in the body. Purpose. To structure and summarize scientific findings on the role of thyroid hormones (T4, T3 and rT3) in the development of hypothyroidism, their effect on inhibiting the growth of cancer cells and the cytotoxic effects of these hormones on thyroid cells. Results and discussion. In spite of a careful study of thyroid function, the use of thyroid hormones and laboratory monitoring in the treatment of various thyroid pathologies remains debatable up to now. In particular, it concerns LT4 + LT3 combination and the role of reversible T3. This is due to a complex regulation system depending on many factors: hormonal homeostasis, nutritional factors, physiological conditions, etc., which together maintain appropriate thyroid functioning. LT4 monotherapy remains the standard method of replacement therapy, however, according to the ETA recommendations, it is possible for individual patients to prescribe combination therapy LT4 + LT3 as an experimental approach. The use of the rT3 test as a prognostic / diagnostic indicator for monitoring the therapy of patients receiving L-thyroxine therapy is discussed. The use of L-thyroxine as a thyrotropic suppressive therapy in the treatment of thyroid cancer requires careful dose adjustment depending on the health status of each patient, the risk of recurrence, which requires monitoring and dynamic reassessment. Long-term suppressive therapy of LT4 can affect metabolism, contributing to weight loss. Conclusions. Given the analysis of the literature, which covered 20 years, today L-T4 monotherapy is the standard therapy for patients with hypothyroidism. LT4 + LT3 combination therapy can be recommended in patients receiving L-T4 treatment with complaints characteristic of hypothyroidism despite normal TSH levels, with the exception of other chronic and concomitant autoimmune diseases that may be the cause.