His Thyroid Cancer didn't take up Radioiodine. Was this a true test, or hidden contamination by unknown iodine intake?

41 year old male had a well differentiated papillary thyroid cancer removed and was in the process of receiving radioiodine treatment, when it was noted on Ultrasound that a mass was seen in the thyroid area. The biopsy, and
washings for cancer marker,thyroglobulin were positive.
The whole body scan with the TSH > 110 was negative although there was an obvious cancer mass present. I put the patients on low iodine diet, but do not routinely get
24 hour urine iodine to look for unknown sources of iodine contamination. The failure to take up iodine is not a good sign, therefore, I needed to be sure this was true.After his surgery, to remove the mass and strip the nodes, I have set up a protocol to insure there was no iodine contamination. He denied any iodine contrast before the first body scan, and claimed to be strictly on the L.I.D.
The patient will be withdrawn from LT4 and then withdrawn from LT3. 2 weeks of L.I.D will follow. A 24 hour urine for iodine and creatnine will be done. Lithium, a drug known to block release of iodine from the thyroid, will be given for 5 days to "hold" the iodine in any remaining thyroid cancer, or normal thyroid tissue. One last try at getting uptake will be with 100-150 Millicuries I/131. A body scan at day 7 post therapy will tell us if he truly has a thyroid cancer that does not allow us the ability to use radioiodine in his future care. The loss of the ability to take up radioiodine is a sign of a more aggressive tumor. Alternative methods to follow patients, will have to include, in addition to ultrasound, thyroglobulin, MR, and CT, a P.E.T. scan. However positive areas on P.E.T. can not be treated at the present time, unless they can be found on CT, and then surgically removed.

Happy New Year,

Dr.G.