Table 1.
Characteristics of study subjects and the prevalence of thyroid-related parameters in males and females.
| Variable | Total | Male | Female | p-Value |
|---|---|---|---|---|
| N (%) | 3401 (100.0) | 1772 (52.1) | 1629 (47.9) | |
| Age, years, median (IQR) | 10.0 (9.0, 11.0) | 10.0 (9.0, 11.0) | 10.0 (9.0, 11.0) | 0.979 |
| BMI, kg/m2, median (IQR) | 17.1 (15.5, 20.0) | 17.5 (15.7, 20.8) | 16.7 (15.3, 19.1) | <0.001 |
| Region | ||||
| Urban | 2048 (60.2) | 1051 (59.3) | 997 (61.2) | 0.262 |
| Rural | 1353 (39.8) | 721 (40.7) | 632 (38.8) | |
| Thyroid function indexes | ||||
| FT3, pmol/L, median (IQR) | 6.8 (6.2, 7.4) | 6.8 (6.3, 7.5) | 6.7 (6.1, 7.3) | 0.004 |
| FT4, pmol/L, median (IQR) | 18.0 (16.4, 19.6) | 18.2 (16.5, 19.7) | 17.8 (16.2, 19.4) | <0.001 |
| TSH, µIU/mL, median (IQR) | 2.6 (1.9, 3.5) | 2.6 (1.9, 3.6) | 2.5 (1.8, 3.4) | 0.110 |
| Tg, ng/mL, median (IQR) | 12.2 (8.2,18.2) | 12.1 (8.4, 17.7) | 12.4 (7.9, 18.7) | 0.528 |
| Iodine nutrient levels | ||||
| UIC, µg/L, median (IQR) | 205.2 (127.0, 313.6) | 216.0 (134.0, 323.0) | 195.7 (118.0, 307.0) | <0.001 |
| UI/Cr, µg/g, median (IQR) | 167.8 (111.5, 241.8) | 166.7 (112.1, 239.9) | 168.3 (111.3, 243.3) | 0.619 |
| Thyroid disorders | ||||
| Positive TPOAb, n (%) | 71 (2.1) | 20 (1.1) | 51 (3.1) | <0.001 |
| Positive TgAb, n (%) | 92 (2.7) | 26 (1.5) | 66 (4.1) | <0.001 |
| Positive thyroid antibodies, n (%) | 121 (3.6) | 36 (2.0) | 85 (5.2) | <0.001 |
| Subclinical hypothyroidism, n (%) | 469 (13.8) | 256 (14.4) | 213 (13.1) | 0.247 |
| Thyroid nodules, n (%) | 798 (23.5) | 380 (21.4) | 418 (25.7) | 0.004 |
p-values are for trends between males and females. Bold remarks indicate statistically significant differences. Abbreviations: BMI, body mass index; IQR, interquartile range; TSH, thyroid-stimulating hormone; FT3, free triiodothyronine; FT4, free thyroxine; Tg, thyroglobulin; UIC, urinary iodine concentration; UI/Cr, urinary iodine-to-creatinine ratio; TgAb, thyroglobulin antibody; TPOAb, thyroid peroxidase antibody.