Table 1.
Baseline characteristics of the patients based on free T4 levels.
| Clinical Parameters | Q1 (free T4 <1.13 ng/mL) |
Q2 (1.13–1.24 ng/mL) |
Q3 (1.25–1.34 ng/mL) |
Q4 (free T4 >1.35 ng/mL) |
p Value |
|---|---|---|---|---|---|
| Patients (n, %) | 877 (24.3) | 906 (25.1) | 834 (23.4) | 931 (27.2) | |
| Age (years) | 40.1 ± 0.5 | 44.9 ± 0.5 | 42.2 ± 0.6 | 38.5 ± 0.5 | <0.001 |
| Sex (male n, %) | 295 (36.1) | 401 (47.6) | 405 (51.2) | 635 (70.9) | <0.001 |
| BMI (Kg/m2) | 23.9 ± 0.1 | 24.0 ± 0.1 | 23.61 ± 0.1 | 23.6 ± 0.1 | 0.047 |
| Smoking (n, %) | 134 (16.1) | 186 (20.4) | 192 (24.4) | 258 (28.1) | <0.001 |
| Heavy alcohol consumption (n, %) | 99 (11.4) | 99 (11.5) | 108 (12.8) | 125 (14.0) | 0.395 |
| Physical activity (n, %) | 144 (16.5) | 141 (14.8) | 145(17.7) | 169 (17.4) | 0.460 |
| Diabetes mellitus (n, %) | 36 (3.6) | 31 (3.3) | 35 (4.9) | 27 (2.9) | 0.258 |
| Urine iodine: (mcg/g) | <0.001 | ||||
| Q1 (<86.20) | 176 (20.0) | 201 (22.7) | 204(23.7) | 303(32.7) | |
| Q2 (86.2–165.4) | 170 (18.5) | 223 (23.7) | 234 (28.9) | 260 (28.4) | |
| Q3 (165.5–404.3) | 240 (28.5) | 228 (25.7) | 207 (26.1) | 201 (20.4) | |
| Q4 (>404.3) | 291 (32.9) | 254 (27.9) | 189 (21.4) | 167 (18.4) | |
| Total cholesterol (mg/dL) | 193.9 ± 1.6 | 192.4 ± 1.3 | 189.2 ± 1.5 | 187.2 ± 1.2 | 0.001 |
| Triglyceride (mg/dL) | 144.4 ± 6.0 | 145.4 ± 5.0 | 138.2 ± 4.9 | 129.4 ± 4.1 | 0.056 |
| HDL-cholesterol (mg/dL) | 51.0 ± 0.5 | 50.3 ± 0.4 | 51.5 ± 0.5 | 51.2 ± 0.5 | 0.328 |
| LDL-cholesterol (mg/dL) | 114.0 ± 1.5 | 113.0 ± 1.3 | 110.1 ± 1.2 | 110.1 ± 1.2 | 0.074 |
| non- HDL-cholesterol (mg/dL) | 142.9 ± 1.6 | 142.1 ± 1.2 | 137.8 ± 1.5 | 136.0 ± 1.2 | <0.001 |
Data are expressed as mean ± standard error or number including percentage; Free T4: free thyroxine; BMI: body mass index; HDL: high-density lipoprotein; LDL: low-density lipoprotein.