Digoxin Metabolism in Hypo- and Hyperthyroidism

Abstract

Tritiated digoxin was given to 13 patients when hyperthyroid, 10 when hypothyroid. Frequent serum samples were obtained, and all urine and stools were collected for 7 days. Four patients received digoxin orally. These results are compared to 25 euthyroid patients given tritiated digoxin reported in previous studies. The dominant serum half-time of digoxin was not significantly altered; however, there was a significant difference in the serum levels of digoxin. Serum levels were higher in myxedema, intermediate in euthyroid patients, and lowest in hyperthyroid patients. Digoxin excretion was unchanged. An objective basis for administration of small doses of digoxin in myxedema and larger doses of digoxin in hyperthyroidism has been provided.