Prolonged iodine clearance with a depletion regimen for thyroid carcinoma: concise communication.
Prior studies suggested iodine depletion as a means of enhancing radioiodine uptake into metastases from well-differentiated thyroid cancer. Data are not available regarding the secondary effects of this maneuver on iodine clearance and on total-body radiation. Accordingly we have measured inorganic iodine clearance, total body iodine, tumor and total-body retention of radioactive iodine before and during a diet-and-diuretic regimen designed to induce iodine depletion. Total-body iodine decreased by 25% to 66% (p less than 0.05). The amount of radioiodine taken up and retained by tumor tissue increased 146% (range 48-243%) following the depletion regimen in three studies (two patients). However, because the iodine clearance decreased by 56% (range 40-71%), the total-body radiation per standard 150-mCi dose increased by 68% (range 19-111%). Consequently, the increase in lesion irradiation relative to the increment delivered to the total body was only 46% (range 24-82%). We conclude that iodine-depletion regimens are less effective than prior studies suggest.
D000328:Adult; D002277:Carcinoma / Q000000981:diagnostic imaging / Q000378:metabolism* / Q000628:therapy; D004032:Diet; D004232:Diuretics / Q000627:therapeutic use; D005260:Female; D006801:Humans; D007455:Iodine / Q000008:administration & dosage / Q000378:metabolism*; D007457:Iodine Radioisotopes; D008657:Metabolic Clearance Rate; D008875:Middle Aged; D009362:Neoplasm Metastasis; D011184:Postoperative Period; D011829:Radiation Dosage; D011877:Radionuclide Imaging; D013964:Thyroid Neoplasms / Q000000981:diagnostic imaging / Q000378:metabolism* / Q000628:therapy; D013997:Time Factors
D004232:Diuretics; D007457:Iodine Radioisotopes; D007455:Iodine