Cardiovascular Effects of Cumulative Doses of Radioiodine in Differentiated Thyroid Cancer Patients with Type 2 Diabetes Mellitus.

Radioiodine ( 131 I) therapy for differentiated thyroid cancer (DTC) involves exposure of the whole body, including the heart, to ionizing radiation. This exposure to the subsequent risk of heart disease is uncertain, especially in patients with DTC associated with type 2 diabetes mellitus (DTC/+T2DM). The current study aimed to assess the relationship between left ventricular ejection fraction (LVEF), high cumulative 131 I dose, and peripheral blood parameters in patients with DTC/-T2DM and DTC/+T2DM. The study enrolled 72 female patients with DTC/-T2DM and 24 with DTC/+T2DM who received cumulative 131 I doses above 150 mCi (5.55 GBq). LVEF was lower in patients with concomitant T2DM than those without ( p < 0.001). The cumulative 131 I dosage was inversely correlated with LVEF only in DTC/-T2DM patients ( r = -0.57, p < 0.001). In the DTC/+T2DM group, LVEF was negatively associated with absolute platelet count ( r = -0.67, p < 0.001) and platelet-to-lymphocyte ratio ( r = -0.76, p < 0.001). Our results demonstrate that exposure to high cumulative 131 I doses has different cardiovascular effects in DTC/-T2DM and DTC/+T2DM.