Michael Kleerekoper, MD, MACE, has joined the faculty at the University of Toledo Medical School where he is Professor in the Department of Internal Medicine and section chief of the Endocrinology Division. The author of numerous journal studies, Dr. Kleerekoper serves on the editorial boards for Endocrine Today, Endocrine Practice, Journal of Clinical Densitometry, Journal of Women's Health, Osteoporosis International and Calcified Tissue International. Dr. Kleerekoper is also a founding board member of the newly formed Academy of Women’s Health.

Out-of-control RAI uptake

Over a period of 6 weeks I received hard to believe results from radioactive iodine uptake in three patients with well-documented hyperthyroidism.

In each of them, the 6-hour uptake was 85% to 90% and 90% to 92% at 24 hours.

The third patient is the most surprising. When I referred her for management, her thyroid-stimulating hormone was low at 0.11 (reference range: 0.11-5.0), her free T3 very high at 19.4 (reference range: 2.2-4.0) and her free T4 was 4.20 (reference range: 0.71- 1.85).

Each of these three patients has done well post-ablation, but they do need and are taking thyroid replacement.

I am in discussion with the nuclear medicine radiologists about these unusual data, but none of us can find a satisfactory explanation. I have carefully gone through PubMed and found nothing that could explain these results and also looked at seemingly relevant articles in JCEM. I am still in the dark.

My excellent radiology colleagues are very careful in determining the appropriate dose of RAI and there was nothing unusual in these patients.

I have contacted some thyroid expert colleagues for an explanation but to date there is no meaningful answer.

As is often with my blogs, any advice you can provide is needed.