Metabolism The main pathway of thyroid hormone metabolism is thru sequential deiodination. Approximately 80% of circulating T3 is derived from peripheral T4 by monodeiodination. The liver is the major website of degradation for each T4 and T3. There aren't any animal experiments conducted with liothyronine through pregnancy. Liothyronine Sodium Tablets, http://www.t3tiromel.com