The effect of lithium on thyroid functioning: A controlled study

Abstract

THE EFFECTS of lithium on thyroid function have recently been reviewed by SHOPSIN.~ Anecdotal reports of hypothyroidism and goiter are described. Controlled human studies have been done by SEDVALL et aL2 and COOPER and SIMPSON.~ SEDVALL et al.2 gave lithium to 14 manic-depressives and used 11 patients receiving phenothiazines, with other diagnoses as controls. The lithium treatment was begun, “about one week after admission to the hospital. . . . Tests of thyroid function were performed during the first week after admission to hospital and 10 to 14 days later. At the latter time lithium treatment in the manic-depressive patients had been maintained for 7 to 20 days.” A personal communication from the senior author indicates that the initial thyroid function tests were all done prior to initiation of lithium, and the second series of tests were done 7 -20 days after lithium was begun, and not 10-14 days as published. Compared to the first test, there was a significant decrease in protein bound iodine (PBI) and a significant increase in the percentage of orally administered radioactive iodine (24 hr RAIl”l) in the thyroid after 24 hr, in the lithium treated manic-depressed patients. There were no changes in the control patients. It is difficult to evaluate the significance of these results because the control group had different diagnoses and received an active drug that may affect thyroid function tests.4 COOPER and SIMPSON~ compared PBI and free thyroxine in 25 manic-depressives two weeks after initiating lithium treatment to 139 other psychiatric admissions (excluding organic psychoses) who had blood drawn while drug free. The PBI and free thyroxine were significantly reduced in the lithium group. They also compared RAIU (24 hr) before, and 12-16 weeks after lithium treatment in 12 manic-depressives and found a significant increase following lithium treatment. BURROW et aL5 studied 9 patients before and after 3-4 weeks of lithium therapy. Some patients received concomitant psychotropic drugs and perhaps diphenylhydantoin or oral contraceptives. The patients were hospitalized and diagnosed as having “mood disorders” although one patient may have been hospitalized for a seizure disorder. They found that *We wish to acknowledge the help we received in the statistical computations from Mrs. Dolores Millan