[Measurement of intrathyroidal iodine content by X fluorescence: usefulness and application (author's transl)]

X fluorescence quantification of thyroid gland iodine content was performed in 113 subjects. Euthyroid patients averaged 15.6 +/- 4.8 mg in the absence of goiter (18 subjects) and 23.7 +/- 11 mg when the gland was goitrous (11 subjects p less than 0.05). In Grave's disease (28 patients), thyroid iodine content increased significantly (21.7 +/- 11 mg, p less than 0.05. No correlation was found between this parameter and thyroid hormone blood level. During the treatment by carbimazole, patients can be divided in 2 groups; the first group with high initial iodine content (30.3 +/- 15.6 mg 9 patients) decreased it under treatment; on the contrary, the second group with normal initial iodine content (16.9 +/- 7.5 mg 10 patients) increased its iodine content under treatment. No significant difference in T3 and T4 serum levels was found between these two groups. In toxic goiter (6 patients) the initial iodine content was elevated (43.4 +/- 33 mg) and decreased under carbimazole in all the cases. 15 patients with solitary autonomous thyroid nodules were scanned with 99mTc and by X fluorescence imaging. The iodine content of the nodule was 9.9 +/- 4.7 mg; controlateral non suppressed tissue was observed in 11 patients while no 99mTc accumulation was found. The association of these 2 techniques allow to avoid a TSH stimulation test in 70% of the cases. In hypothyroid patients, a low iodine content was found in acquired disease (4.5 +/- 5.6 mg 9 patients); it was increased in congenital hypothyroid goiter. In iodine load (12 patients) the iodine content was increased especially after lymphography. In the initial phase of subacute thyroiditis (11 patients) X fluorescence showed 127I thyroid stores were still normal (14.3 +/- 11.6 mg) while there was no radioactive uptake.