RESUMO
Thyroid nodules are frequently found, but the vast majority of them are benign. The difficulty in managing thyroid nodules is correctly diagnosing the minority of those who have malignancy. Thyroid fine-needle aspiration cytology (FNAC) with indeterminate cytology continues to raise doubts about the presence of thyroid cancer, leading to an unnecessary thyroidectomy. Circulating miRNAs may be useful as diagnostic and prognostic markers for a variety of cancers, including thyroid cancer. The goal of the present study was to determine the predictive value of serum miRNA-146b expression level for thyroid cancer by estimating its level in a group of euthyroid patients with thyroid nodules with indeterminate FNAC results. This cross-sectional study included 45 euthyroid patients with indeterminate thyroid nodules who visited the Endocrine Outpatient Clinic and Endocrine Surgical Ward at Ain Shams University Hospitals. For all patient thyroid profiles, ultrasound of the thyroid gland and FNAC of the thyroid nodule were performed. In addition, preoperative assessment of serum microRNA-146b expression by real-time PCR was achieved and the results correlated with post-operative thyroid histopathology. There was no difference in serum miRNA-146b expression between patients with benign thyroid nodules versus patients with malignant nodules (p= 0.789). The risk of malignancy increased with the increase in size of the dominant thyroid nodules, as larger nodules had a higher risk of malignancy (p= 0.027). In conclusion, in euthyroid patients with indeterminate thyroid nodules, serum miRNA-146b is a poor predictor of thyroid malignancy, however, the larger the nodule size, the higher the risk of cancer.