Table 1. Baseline characteristics of study subjects by study group.
| Variable | PTC group (n=182) | Benign nodule group (n=185) | Control group (n=180) | P-value |
|---|---|---|---|---|
| Age (years) | 35.53±10.90 | 35.11±13.01 | 34.67±12.96 | 0.917 |
| Sex, female | 145 (79.6) | 148 (80.1) | 145 (80.5) | 0.986 |
| BMI (Kg/m2) | 24.83±2.99 | 24.38±3.75 | 24.27±3.99 | 0.728 |
| FT4 (ng/dl) | 1.26±0.31 | 1.27±0.19 | 1.29±0.36 | 0.683 |
| FT3 (pg/ml) | 3.73±0.59 | 3.86±0.48 | 3.59±0.49 | 0.357 |
| TSH (mIu/L) | 2.49±1.03a | 1.79±1.09b | 2.00±1.11b | <0.001 |
| Selenium (µg/l) | 94.89±19.18a | 121.04±21.07b | 134.00±28.91c | <0.001 |
| Selenium deficiency (<70) | 24 (13.1)a | 0 (0.0)b | 7 (3.8)c | <0.001 |
Data are shown as number (%) or mean±SD. P-values were determined by one-way ANOVA, Pearson χ2 test, or Fisher's exact test.
BMI: Body mass index, FT4: Free thyroxin, FT3: Free triiodothyronine, PTC: Papillary thyroid carcinoma, TSH: thyroid stimulating hormone.
In numerical variables, mean differences were assessed by the ANOVA test. a, b, c: Post-hoc comparison based on the Bonferroni method. Different superscript letters (a, b, c) in the same row of variables reflect a significant (p < 0.05) difference between the means while the same superscript letters in one row reflect a non-significant difference between the means of three groups.