REPLY:

We thank Sarmiento et al. for their letter supporting our conclusion (1) of the absence of stunning after 185-MGq doses of ¹³¹I, based on their experience. We note with interest their different diagnostic and treatment strategies and respond as follows to the points raised.

Although the majority of patients receive a fairly standard dose, the whole-body scan does play an important role in increasing or decreasing the dose to any individual patient for any given episode. We feel that the ability to calculate a dose based on tangible evidence is an important part of our management strategy.

Although Sarmiento et al. propose avoiding diagnostic whole-body scanning with ¹³¹I, they usually obtain similar information with an uptake and ^99mTc-pertechnetate scan or, if required, with ^99mTc-sestamibi. We agree that any study intended to confirm the presence and assess the amount of residual tissue is valuable in gaining the cooperation of both the referring physician and the patient. However, the diagnostic whole-body scan with 185 MBq ¹³¹I compares favorably with these agents in terms of cost, stunning risk, and treatment delay. The cost of 185 MBq ¹³¹I, with our strategy of delivery well in advance of the calibration date and dispensing in our own radiopharmacy, is approximately ($380/10,360 MBq) × 185 MBq = $6.79 on the day of delivery and thus rises only to a range of $10–$15 before the shipment is used up. This result compares favorably with the cost of the ¹³¹I uptake capsule ($12), in addition to the cost of 185 MBq pertechnetate (approximately $1–$3) and a dose of ^99mTc-sestamibi ($90). Of course, these estimates do not take into account the costs of imaging, but we can assume them to be fairly similar. Regarding the risk factor, we have shown that stunning is not a risk using our strategy. This is a point with which Sarmiento et al. already agree, in light of their experience. Finally, the delay of 72 h introduced by our management enables us to complete the paperwork with the insurance companies and gives patients time to arrange their home and work matters without any clinical detriment.

In addition, our strategy allows us to sit down with patients and their families to show them exactly what the issues are and why the treatment is required. There is no issue as to whether the lack of pertechnetate uptake but positive ¹³¹I uptake indicates a residual tumor. If there is abnormal ¹³¹I uptake on a whole-body scan, treatment is initiated. The development of rapport is, in our opinion, extremely valuable in establishing a strong clinical relationship that will endure through all future follow-up visits. Also, achieving a negative scan at some point after the necessary episodes of therapy and being able to show a negative scan in comparison with prior scans can do wonders for the patient’s morale and ensure further regular follow-up.

Recently, we have added the monitoring of thyroglobulin levels and the use of recombinant thyroid-stimulating hormone to our protocol as well, to further streamline management by offering suitable patients the option of not becoming hypothyroid for follow-up whole-body scanning.

If a decision is reached, usually in a later stage of follow-up, to go after residual tissue surgically (i.e., small amount, low uptake [<1%]), the ¹³¹I remaining may be used with a probe system to assist the surgeon in localization in a reoperated neck.

In conclusion, we are grateful to Sarmiento et al. for confirming the lack of stunning in their experience and also for indicating that some sort of tangible information before ¹³¹I treatment in the form of a scan is useful. In view of the above, we feel that our protocol works well for our patient population, including the first postoperative whole-body scan. We agree that the necessity of this first scan needs to be determined by each center in view of issues related to radiopharmaceutical supply, attitude of the referring physician, and desire of the patient.