STUDIES OF IODOALBUMIN METABOLISM. II. THE EFFECTS OF THYROID HORMONE*

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Abstract
Four patients with myxedema were subjected to tracer studies with I131-iodoalbumin before and after treatment with thyroid hormone. Two were studied by altering their metabolic status during a tracer study and one was given tracer studies in 4 metabolic states. The plasma and urine data were analyzed with reference to an open multicompartment parallel model. The analysis indicated that in myxedema there was an increase in total exchangeable albumin which was confined to the extravascular compartments, a reduction in the rate of albumin synthesis and catabolism, a reduction in the fractional rate of albumin catabolism, an increase in the transcapillary transport rate of albumin, and a reduction in plasma volume. In the studies in which the metabolic status was altered during the tracer experiments the changes in urinary excretion and plasma curves were consistent with the results of steady state experiments in the euthyroid and myxedematous states. Stepwise alteration of the metabolic status in one subject was associated with a stepwise alteration of the values for several of the fractional turnover rates of the multicompartment system.