Measurement of 127I Concentration in Thyroid Tissue by X-Ray Fluorescence

X-ray fluorescence was used to determine the iodine content of surgically removed thyroids that had been preoperatively scanned with /sup 131/I. Iodine concentrations were determined for tissues classified as normal, papillary- follicular carcinoma, chronic thyroiditis, and colloid nodules of adenomatous thyroids. The iodine concentration of these thyroid states varied, with carcinomatous tissue having the lowest concentration and normal tissue the highest. There was considerable overlap among the various pathological states. Nodules showing increased /sup 131/I activity on the presurgical thyroid scan contained no more iodide than normal tissue, while nodules showing decreased /sup 131/I activity contained considerably less iodine. The residual /sup 131/I from the presurgical dose showed a distribution similar to the distribution of stable iodine. The iodine concentration of normal thyroid tissue obtained from autopsy specimens was determined to be about 2.5 times greater than the levels reported in the older literature. (auth)