Endocrine Abstracts

Objective

Radioactive iodine (RAI) therapy is widely used in both diagnosis and treatment of benign and malignant thyroid diseases. It is generally a well tolerated therapy. Bone marrow suppression is often a temporary side effect with a decrease in white blood cells and platelets up to 6–10 weeks. In this study, we aimed to examine hematological changes in patients who received RAI treatment for benign or malignant diseases of the thyroid.

Methods

The records of patients who applied to our endocrinology clinic between January 2016 and January 2019 and received RAI treatment for benign or malignant etiologies were evaluated retrospectively. The demographic data of the patients and data on thyroid disease, additional diseases, and the drugs used were recorded, the patients were grouped according to the etiology and the RAI dose they received. Blood count parameters measured before RAI treatment within 7 days, after RAI treatment and at the last control of the patient were recorded and compared in these patients.

Results

In the study, data of total 202 patients, including 158 women (77.5%) and 44 men (21.6%), were evaluated. 168 of these patients (82.4%) had received RAI treatment due to malign, and 34 benign (16.7%) etiologies. The median age they received RAI was 45 (20–84), while the median dose of RAI was 75 mCi (10–200). Pre-treatment and first control interval was median 44 (18–93) days, and the median time between pre-treatment and last control was 35 (4–56) months. In comparison of hematological parameters before and after treatment, the median leukocyte count was 7.72 (3.89–19.93) × 10⁹/l before treatment, while it was significantly reduced 6.27 (0.86–14.5) × 10⁹/l at the first control after treatment and 6.78 (3.58–10.8) × 10⁹/l at the last control. Similarly, a decrease in neutrophil and lymphocyte counts was detected after treatment. While the median hemoglobin value was 13.95 (8.8–17.2) g/dl before RAI treatment, it was 13.5 (7.8–17.3) g/dl and 13.5 (6.7–17.6) g/dl at the first and last control after treatment, respectively. The median platelet count was 283 (149–563) × 10⁹/l, and it was 250.5 (134–507) × 10⁹/l at the first post-treatment control and 266.5 (116–539) × 10⁹/l at the last control. While the median value of mean platelet volume(MPV) was 10.8 (8.5–13.8) fL before treatment, it was 10.15 (7.6–13.1) fL and 8.2 (6.6–11.1)fL, respectively, in controls.

Conclusion

In our study, a significant decrease was found in the leukocyte, neutrophil, lymphocyte, platelet counts, hemoglobin levels and mean platelet volumes in the post RAI treatment period. According to these findings, it can be thought that the decrease in hematological parameters continues not only in the acute period but also in the chronic period after RAI.