By assuming a three-compartment model, kinetic analysis of peripheral hyroxine distributions in various organs was represented by the alues calculated on the basis of the disappearance curve of 131I-T4 radioactivity in the serum, time　dependent curve of radioactivity over the liver　and urinary excretion of 131I-T4 in attempts to clarify the kinetic distribution　of the thyroxine and the time　dependent pool size of thyroxine in each　compartment such as serum pool, liver pool, and the other pool,　As a result it has been demonstrated that pool size3 of tyroxine, in
the serum, liver and the other pool are enlarged in　hyperthyroidism, while　they are decreased in　hypothyroidism in respective pools.　We have recognized the reduction in the values of the liver pool size　of 131I-thyroxine and 131I-thyroxine excretion into the bile, while the increase　of 131I-thyroxine excretion into the urine in the cases of chronic hepatitis　and cirrhosis of the liver, but the thyroxine concentration in the serum to
remain within the normal level in liver diseases. As a result of the reduction　in the liver pool size of 131I-thyroxine and in its uptake into the liver,　the other pool size enlarges to compensate the reduction and the function
of the other pool is elevated.</p
