Table 2 Logistic regression analysis of the significant risk factors in association with bilateral PTMC

Final pathological factors

Tumor size (≥7 mm/<7 mm)

1.054

0.378

0.005^a

2.869

1.366–6.023

Multifocality

3.390

0.601

<0.001^a

29.657

9.140–96.234

Constant

−2.028

0.286

Preoperative factors

Preoperative tumor size(≥ 7 mm/<7 mm)

0.875

0.357

0.014^a

2.398

1.192–4.824

Preoperative multifocality

3.174

0.668

<0.001^a

23.900

6.456–88.475

Constant

−1.806

0.263