Thyroid nodules (TN), one of the most common clinicalthyroid diseases, have become increasingly prevalentworldwide. The prevalence of TN by palpation is 4–7%,while the prevalence by ultrasound is 13–67% [1]. It isestimated that 5% of clinically apparent thyroid nodulesmight become malignant. Furthermore, nontoxic nodulescould develop into carcinomas [2]. Accordingly, the associated risk factors have received much attention in recentyears