In an univariate logistic regression analysis, the OR for hypothyroidism in patients with a positive TPO Ab status was 3.29 (95% CI: 1.35–8.22; P  = 0.009) in period 1 and 2.92 (95% CI: 1.17–7.41; P  = 0.022) in period 2. This evidence concerns the gene TPO and hypothyroidism.