Radioactive Iodine Treatment After Thyroidectomy: Impact on Blood Cell Counts
Posted: Friday, September 11, 2020
Patients who received moderate-dose radioactive iodine treatment (100–150 mCi) after total thyroidectomy for differentiated thyroid cancer experienced a statistically significant temporary decline in white blood cell (WBC) counts and hemoglobin levels 1 week after treatment—but not in platelet counts—according to a study published in the Endocrine Journal by a Korean research team. However, the investigators reported that all blood components had recovered within 1 year.
Bo Hyun Kim, MD, PhD, of Biomedical Research Institute, Pusan National University Hospital, Korea, and colleagues shared their clinical take on their study findings: “Physicians treating differential thyroid cancer patients should not decrease the use of moderate-dose radioactive iodine treatment when the benefits of ablation are likely to outweigh the risks.”
A total of 180 patients with differentiated thyroid cancer who received radioactive iodine treatment underwent blood tests before and after treatment. To assess bone marrow suppression, the investigators compared peripheral blood counts at baseline with those obtained at 1 week, between 1 and 6 months, and between 6 and 12 months after treatment. Most patients (81%) were women, and all underwent total thyroidectomy for papillary thyroid cancer. More than half of the study patients (54.5%) received a radioactive iodine dose of 100 mCi, and the others received a dose of 150 mCi.
There was a significant decrease in WBC count (P < .001) and hemoglobin level (P = .001) 1 week after treatment. Although lymphocyte counts were the main reason for the drop in WBC count, there appeared to be no decrease in neutrophil count. Of note, platelet counts were not found to be significantly changed at 1 week, although they were altered within 6 months (P < .001). However, within 6 months, the WBC count had recovered; and within 12 months, lymphocyte and platelet counts had recovered.
Disclosure: The study authors reported no conflicts of interest.