Herein, based on the primary function of MMPs in tumor progression and metastasis, we sought to specify the presence of MT4-MMP and MT6-MMP in the circulating system of patients with thyroid nodules, including malignant nodules (PTC) or benign nodules (multinodular goiter; MNG) and explore their potency, together or alone, as diagnostic circulating biomarkers. The gene discussed is MT4; the disease is thyroid nodule.