Chronic anemia and thyroid function

Abstract

Anaemia is a global public health problem affecting both developing and developed countries with major consequences for human health as well as social and economic development. It occurs at all stages of the life cycle, but is more prevalent in pregnant women and young children. Iron deficiency anaemia (IDA) impairs thyroid metabolism in animals and human and may negatively affect growth and develpment of children. On the other hand both overt and subclinical hypothyroidism are associated with anemia and adding iron to thyroxine therapy improves both conditions compared to thyroxine therapy alone. In addition patients with chronic hemolytic anemia requiring repeated blood transfusion have high prevalence of hypothalamic-pituitary thyroid axis. Both primary hypothyroidism and central hypothyroidism occur in these patients with increasing prevalence with age, severity of the anemia and higher ferritin concentration denoting poor chelation. Proper blood transfusion and intensive chelation appears to prevent deterioration of thyroid function and in many cases can reverse thyroid pathology. Physicians treating these forms of anemia should be aware of thyroid disorders in these patients for early screening, prevention and proper management of any thyroid dysfunction.

Keywords: : iron , iron deficiency anemia (IDA), thalassemia, sickle cell disease, thyroid , free thyroxine, TSH..

Figure 1

Mechanisms of thyroid dysfunction in chronic anemias Legend: ID = iron deficiency, IDA = iron deficiency anemia, T3 = triiodothyronine, T4 = thyroxine, TSH = thyrotrophic hormone, TPO = thyroid peroxidase