Use of lithium as an adjunct to radioiodine therapy of thyroid carcinoma

Abstract

The effect of lithium on iodine kinetics after oral131I-iodide was studied in an athyreotic patient with follicular thyroid carcinoma. Lithium decreased the disappearance rate of131I from the whole body and from a tumor mass in the patient’s thigh from control values of 0.126/day and 0.122/day to 0.090/day and 0.049/day, respectively, while having only a minimal effect on the rate of131I disappearance from blood. The increased tumor131I retention would be expected to increase the therapeutic:toxic ratio of131I. However, a subsequent therapeutic dose of131I-iodide given with lithium was accompanied by an unanticipated increase in blood131I and, therefore, in whole body radiation, resulting in significant bone marrow depression. Although lithium may be a useful adjunct in131I therapy of functional thyroid carcinoma, it must be used cautiously in future studies. © 1976 by The Endocrine Society.