Iron and ferritin deficiency in women with hypothyroidism and chronic lymphocytic thyroiditis - systematic review

Iron is one of the essential microelements necessary for maintaining the body's homeostasis. It serves various roles, including being a crucial component in the proper structure of many enzymes and supporting the transport of oxygen and electrons. Its deficiency can lead to anaemia, which is a common clinical condition often associated with thyroid diseases. Iron deficiency is one of the most common nutritional deficiencies, and its prevalence is strongly associated with socioeconomic status. It is the primary cause of anaemia in 42% of children and 50% of women. Importantly, iron deficiency is placed among the top 5 causes of disability in women. Thyroid peroxidase (TPO) is an enzyme essential for the production of thyroid hormones, and iron is a key factor in its proper functioning. Therefore, in the case of iron deficiency, the activity of this enzyme is also reduced. Iron is also a factor that is important in epigenetic modification processes, and its deficiency may contribute to genomic changes potentially promoting the development of autoimmune thyroid diseases. Adequate supplementation in patients with Hashimoto's disease is one of the crucial elements of effective therapy. In addition to iodine, selenium, and magnesium supplementation, attention should be paid to proper iron intake. Iron is an element that is a component of the heme enzyme- thyroid peroxidase, which owes its activity to the binding of haem, and its function is the production of thyroid hormones. Iron can be delivered to the body in haem and non-haem forms. The haem form is found particularly in haemoglobin-rich red meat, but also in eggs, fish, and poultry. On the other hand, non-haem iron can be found in legumes, grains, fruits, and vegetables. Our study aimed to gather and summarise knowledge from scientific literature regarding iron deficiency anaemia and its association with hypothyroidism in women, as well as the possible mechanisms and pathogenesis of these conditions. The paper also aims to highlight that considering the high risk of iron deficiency, assessing iron status along with ferritin should be an integral part of additional diagnostic measures in cases of hypothyroidism, particularly Hashimoto's disease.