European Journal of Molecular & Clinical Medicine

Abstract

Introduction:Liver plays vital role in metabolism of thyroid hormone. The liver is the most important organ in the peripheral conversion of tetraiodothyronine (T4) to T3 by Type 1 deiodinase1,2. Type I deiodinase is the major enzyme in the liver and accounts for approximately 30%–40% of extrathyroidal production of T3, it can carry out both 5’-and 5-deiodination of T4 to T3. Moreover, the liver is involved in thyroid hormone conjugation and excretion, as well as the synthesis of thyroid binding globulin3. T4 and T3 regulate the basal metabolic rate of all cells, including hepatocytes, and thus modulate hepatic function also. Thyroid diseases affect liver function; liver disease may affect thyroid hormone metabolism; and a variety of systemic diseases affect both the organs. There are clinical and laboratory associations between thyroid and liver diseases. Patients with chronic liver disease may have thyroiditis, hyperthyroidism, or hypothyroidism. Patients with subacute thyroiditis or hyperthyroidism may have liver function abnormalities, which return to normal as the thyroid function improves.4 Available studies suggest that the most frequent change is decreased total T3 and free T3 concentration which is reported to be associated with severity of hepatic dysfunction. Serum T4 levels either remain normal or slightly low. However, serum TSH levels remain normal or slightly raised. These changes in thyroid hormone levels are so well established that these can be used as a sensitive index of liver function.