Although several reports describe depression of circulating cellular elements in the blood of patients treated with radioactive iodine (RAI) for differentiated thyroid carcinoma (DTC), little is known about changes in platelet aggregation, cytokines and complement levels after RAI treatment. We selected 14 patients with DTC (8 females and 6 males; mean age: 34±10 yr) who received the same dose of 131I therapy for thyroid cancer. Fourteen sex -and age- matched normal subjects (mean age: 36±5 yr, 8 female and 6 males) were enrolled as controls. All patients were in class III and none had accompanying thyroiditis. Serum samples for IL-6 and TNF were collected 1 day before and at 2, 4 and 6 months after the radioiodine treatment. At each visit, peripheral blood count, platelet aggregation, immunoglobulins, complement levels and lymphocyte subpopulations were evaluated. WBC counts, hemoglobin, platelet and total lymphocyte count and TNF- levels did not change significantly after RAI administration. CD19 counts decreased significantly at 2 months. There were no other significant changes in lymphocyte subpopulations. IL-6 levels increased significantly 2 months following treatment. A significant fall in C3c and C4 levels was observed 4 months after treatment. No significant changes were found in pre- and after-treatment immunoglobulin levels. Platelet aggregation induced with ADP, collagen and epinephrine also did not show any difference before and after treatment. We conclude that RAI adminisration in DTC patients in associated with a significant increase in circulating IL-6 levels and a reduction in CD19 cound and complements.
Keywords: Radioiodine theraphy, differentiated thyroid carcinoma, immune parameters, hemat ological parameters