TPO and anemia (phenotype): The underlying mechanisms explaining the association between anaemia and thyroid function remain unclear; a few studies have shown that iron deficiency might affect thyroid function due to an impaired efficacy of TPO activity as well as the conversion from T4 to T3 or on the Krüppel-like factor 9, an essential factor for erythroid maturation and T lymphopoiesis [33, 34].