TPO and nodular goiter: In the subgroup with normal levels of the TPO antibody, a larger size (p < 0.05) and concurrent nodular goiter (OR = 1.982, 95%CI = 1.158–3.391, p < 0.05) were the risk factors, while in patients with high levels of the TPO antibody, a larger size, extrathyroidal extension (p < 0.05), and younger age (OR = 2.183, 95%CI = 1.420–3.356, p < 0.05) were the risk factors (p < 0.05) (Table 5).