At 1 and 6 months after radioactive iodine therapy, the WBC count has fallen twice as much in diabetics not taking metformin compared to those taking metformin; at one year, the WBC count was back to normal in metformin patients but still 20% lower than baseline in those that were not taking metformin. The platelet count fell the most, though similarly in both groups during the first 6 month, but at 1 year was only 16% below baseline in the metformin group compared to 40% below baseline in the non-metformin group. There was no change in red-cell count and the dose of metformin did not mater.
WHAT ARE THE IMPLICATIONS OF THIS STUDY?
This study shows that the WBC and platelet counts do indeed fall after radioactive iodine therapy and that metformin appears to be protective in preventing this fall in patients with diabetes. At this point, since the fall in these cells does not appear to be cause a significant clinical effect, metformin should not be used in non-diabetic patients for this purpose but may be considered in patients that have low blood counts from other co-existing medical problems. Further research needs to be done on whether metformin can decrease some of the effects of chemotherapy and radiation on the bone marrow for other cancer treatments.
— Melanie Goldfarb MD, MS, FACS, FACE
ATA THYROID BROCHURE LINKS
Radioactive Iodine Therapy: http://www.thyroid.org/radioactive-iodine/