The development of hyperparathyroidism after radioactive iodine (RAI) thera
py has been reported in 38 cases in the literature. However, the developmen
t of a parathyroid adenoma after RAI therapy for a hyperfunctioning multino
dular goiter has not been reported. This report describes the pathologic an
d operative finding on a patient with both hyperthyroidism and hyperparathy
roidism, which was diagnosed after previous RAI therapy for a toxic, multin
odular goiter.