The iodine concentration in benign and malignant thyroid nodules measured by X-ray fluorescence

Iodine concentration was measured by X-ray fluorescence in 48 normal thyroid glands obtained at autopsy and in 91 surgical thyroid specimens with a variety of abnormalities. The iodine concentration in normal thyroids ranged from 0.02 to 3.12 mg/g of tissue with a mean value of 1.03 +/- 0.67 mg/g. The concentrations in pathological specimens were generally lower with the lowest values found in thyroid cancers. Sixteen (76%) of 21 malignant thyroid specimens analysed had undetectable iodine (less than 0.02 mg/g) whereas 22 (96%) of 23 benign nodules had measurable iodine concentrations. The detection of iodine in a thyroid nodule by X-ray fluorescence pre-operatively would significantly decrease the probability of malignancy and the need for surgical excision.