Peculiarities of the anemic syndrome course with thyroid dysfunction

This article was created on the basis of a literature review in the Web of Science, PubMed and Scopus databases and analyzes information on the prevalence, classification, etiopathogenetic mechanisms of anemia, evaluation of data from clinical studies and meta-analyses on the course of anemic syndrome in thyroid diseases. Anemia and thyroid dysfunction are common phenomena that often occur simultaneously. According to modern recommendations, it is worth evaluating the function of the thyroid gland when investigating anemia. With thyroid dysfunction, normocytic anemia is the most common, and microcytic and macrocytic anemias occur less often. The combination of anemia with thyroid diseases is an important problem for clinicians. Thyroid hormones have a direct effect on the proliferative capacity of the erythroid progenitor, which may be related to the mechanism of erythropoietic dysfunction in human thyroid diseases. Anemia, especially iron deficiency, in turn, affects a decrease in the level of thyroid hormones against the background of weakened thyroid function of the pituitary gland. The most frequent cause of anemia in hypothyroidism is bone marrow suppression due to thyroid hormone deficiency, as well as insufficient production of erythropoietin due to a decreased need for O2. Hyperthyroidism is associated with an increased number of erythrocytes, because there is an excessive need for tissues in oxygen, and therefore, the secretion of erythropoietin is increased. In autoimmune thyroid disease, a high prevalence of vitamin B12 deficiency and, especially, pernicious anemia is observed. Anemia in Graves’ disease resembles anemia of chronic disease and is associated with activation of nonspecific inflammation. Aplastic anemia, which is the result of the thyroid dysfunction, is rare. It occurs as a side effect in patients with autoimmune hyperthyroidism who take antithyroid drugs.