title: Use of adjunctive potassium iodide after radioactive iodine (131I) treatment of Graves' hyperthyroidism.
abstract: One hundred and nineteen patients with Graves' hyperthyroidism who were treated with 131I alone or 131I followed by potassium iodide (131I + KI) were studied retrospectively. Patients in both groups who required only a single dose of 131I for successful treatment of hyperthyroidism had similar age, gland size, 24-h radioactive iodine uptake, pretreatment serum T4 concentrations, and radioactive iodine treatment dose. Seven weeks after 131I, mean serum T4 concentrations were 12.3 +/- 6.1 micrograms/dl (mean +/- SD) in patients who received 131I alone and 8.0 +/- 3.9 micrograms/dl in patients who received 131I + KI (p less than 0.001). Sixty percent of the patients who received 131I + KI and remained euthyroid 1 yr after 131I treatment developed documented transient hypothyroidism while receiving KI (serum T4, 1.4 +/- 0.9 micrograms/dl). Patients with transient hypothyroidism receiving KI had larger estimated thyroid gland weights when hypothyroid than patients whose hypothyroidism was permanent (32 +/- 6 vs. 16 +/- 11 g; P less than 0.001). The overall incidence of hypothyroidism 1 yr after treatment with 131I was 58% in each of the two groups. Sixteen percent of each group were not successfully treated by a single dose of 131I and required further therapy. Adjunctive KI effectively treated thyrotoxicosis more rapidly than 131I alone without adversely affecting outcome at 1 yr; however, patients taking KI more often develop transient hypothyroidism.
mesh_terms: D000328:Adult; D004359:Drug Therapy, Combination; D005260:Female; D006111:Graves Disease / Q000628:therapy*; D006801:Humans; D007037:Hypothyroidism / Q000209:etiology; D007457:Iodine Radioisotopes / Q000009:adverse effects / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D011193:Potassium Iodide / Q000009:adverse effects / Q000627:therapeutic use*; D012189:Retrospective Studies; D013974:Thyroxine / Q000097:blood; D014284:Triiodothyronine / Q000097:blood
chemical_list: D007457:Iodine Radioisotopes; D014284:Triiodothyronine; D011193:Potassium Iodide; D013974:Thyroxine