Anemia is defined in 20-60% of the patients with hypothyroidism

Anemia is defined in 20-60% of the patients with hypothyroidism. Anemia in hypothyroidism can be normochromic normocytic, hypochromic microcytic, and macrocytic. Anemia severity is associated with the hypothyroidism degree.

The most frequently encountered anemia type is normochromic normocytic anemia. The most frequent reason for this is the bone marrow suppression due to thyroid hormone deficiency as well as lack of erythropoietin production arising from the reduction in need of O2.

Erythrocyte life cycle in hypothyroidism is normal, and there is hypoproliferative erythropoiesis. Thyroid hormones also increase 2-3 DPG (diphosphoglycerate) levels assisting in the transmission of oxygen into the tissues. Autoimmune thyroid disorders can be seen with other autoimmune disorders.

Pernicious anemia can accompany hypothyroidism as a constituent of polyglandular autoimmune syndrome. Failure of vitamin B12 absorption occurs in pernicious anemia due to intrinsic factor (IF) deficiency and gastric achlorhydria. This is the reason for macrocytic anemia occurrence in hypothyroidism.

Macrocytosis is found in 55% of the hypothyroid patients. Folic acid is another vitamin with impaired intestinal absorption, and causing macrocytic anemia in hypothyroidism. Iron deficiency anemia related to menorrhagia occurs as a result of various hormonal imbalances and also malabsorption which is seen in hypothyroidism.

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