Add Recombinant TSH to Endogenous TSH for Ablation?

Question

I am a family physician in Toronto, Ontario. I am also unfortunately the patient. I will be undergoing I131 treatment following my near total thyroidectomy last month for a mulitcentric follicular variant papillary thyroid carcinoma. It was completely resected. The primary nodule was 2.4 cm with capsular invasion nut no extrathyroidal spread and no blood or lymphatic spread noted. In the contralateral lobe there were two microfoci noted. My stsh currently is around 80 and rising. My endocrinologist has suggested that using rtsh prior to I131 will give a better result. What stsh level is usually aimed for, and what dose of I131 would you use. Given my age (37), the size of the tumour, and its multicentricity, it has been suggested that 150 mCu of I131 was appropriate, but from what I have read, it would seem that most people are using lower doses.

Thanks.

(Name lost in Webspace!)

Response

I feel that your TSH is high enough for a successful ablation of any thyroid remnant. I don't see the need for adding recombinant human TSH. In our experience the addition of endogenous and exogenous TSH does not result in additional advantages over endogenous TSH alone. Regarding the dose, 100 mCi is usually effective (nearly 90% of the cases) and even lower doses such as 30 mCi have been associated with successful ablation in 80% of the cases.

Sincerely,

F. Pacini MD