Table 1.
Baseline characteristics of participants with respect to urinary iodine.
| Characteristics | Total | Low UIC (<100ug/L) | Normal UIC (100-299ug/L) | High UIC (300-399ug/L) | Very high UIC (≥400ug/L) | P-value |
|---|---|---|---|---|---|---|
| 11545 | 4064 | 5507 | 835 | 1139 | ||
| UIC, (ug/L) | 187.86±3.28 | 60.14±0.51 | 175.96±1.03 | 343.55±1.51 | 627.15±7.87 | < 0.001 |
| Age, (Years) | 47.12±0.30 | 45.26±0.37 | 47.67±0.40 | 49.88±0.74 | 49.58±0.67 | < 0.001 |
| Gender, (%) | < 0.001 | |||||
| Female | 5740(49.7) | 2218(55.5) | 2631(48.4) | 375(45.3) | 516(45.2) | |
| Male | 5805(50.3) | 1846(44.5) | 2876(51.6) | 460(54.7) | 623(54.8) | |
| Ethnic, (%) | 0.004 | |||||
| Mexican American | 1813(15.7) | 586(7.7) | 936(9.2) | 129(7.8) | 162(7.6) | |
| Non-Hispanic Black | 2368(20.5) | 889(10.9) | 1137(11.1) | 138 (8.0) | 204 (9.3) | |
| Non-Hispanic White | 5138(44.5) | 1726(68.5) | 2413(68.2) | 422(74.9) | 577(71.5) | |
| Other Race | 2226(19.3) | 863(12.9) | 1021(11.4) | 146 (9.3) | 196(11.6) | |
| Education levels, (%) | 0.02 | |||||
| Above high school | 5940(51.5) | 2182(62.3) | 2794(58.4) | 425(60.0) | 539(57.4) | |
| Below high school | 2875(24.9) | 899(13.9) | 1441(17.1) | 213(16.3) | 322(18.2) | |
| High School Grad/GED or Equivalent | 2730(23.6) | 983(23.8) | 1272(24.5) | 197(23.6) | 278(24.4) | |
| Income, (%) | < 0.001 | |||||
| Above 20000$ | 9116(79) | 3268(87.5) | 4363(86.2) | 651(86.5) | 834(81.4) | |
| Below 20000$ | 2429(21) | 796(12.5) | 1144(13.8) | 184(13.5) | 305(18.6) | |
| Alcohol drinking, (%) | < 0.001 | |||||
| Heavy | 2386(20.7) | 883(22.6) | 1114(22.0) | 165(19.2) | 224(22.7) | |
| Mild | 3798(32.9) | 1339(35.8) | 1858(37.2) | 266(36.6) | 335(32.6) | |
| Moderate | 1820(15.8) | 735(20.9) | 815(16.7) | 123(16.1) | 147(12.3) | |
| No | 3541(30.7) | 1107(20.7) | 1720(24.1) | 281(28.1) | 433(32.5) | |
| Smoking, (%) | 0.08 | |||||
| Former | 2922(25.3) | 961(24.9) | 1420(25.3) | 220(24.3) | 321(28.6) | |
| Never | 6221(53.9) | 2194(53.3) | 2982(55.1) | 457(57.5) | 588(53.4) | |
| Now | 2402(20.8) | 909(21.8) | 1105(19.6) | 158(18.3) | 230(18.0) | |
| Physical activity, (Met) | 567.6±14.3 | 532.6±20.8 | 596.2±22.5 | 612.0±49.3 | 529.7±29.8 | 0.11 |
| Energy, (kcal) | 2189.0±12.0 | 2157.4±21.6 | 2196.5±16.8 | 2305.3±36.4 | 2184.1±38.2 | 0.01 |
| Sodium intake, (mg/d) | 3579.0±22.8 | 3547.2±35.4 | 3603.0±32.3 | 3695.5±78.5 | 3492.5±66.1 | 0.22 |
| Fish and shellfish intake, (%) | 0.03 | |||||
| No | 2290(19.8) | 814(18.7) | 1052(18.3) | 158(18.7) | 266(23.3) | |
| Yes | 9255(80.2) | 3250(81.3) | 4455(81.7) | 677(81.3) | 873(76.7) | |
| Waist, (cm) | 99.19±0.28 | 96.67±0.33 | 100.36±0.38 | 101.98±0.72 | 101.12±0.61 | < 0.001 |
| OGTT glucose, (mmol/L) | 7.29±0.06 | 7.06±0.09 | 7.36±0.08 | 7.57±0.17 | 7.64±0.19 | 0.003 |
| Fasting glucose, (mmol/L) | 5.93±0.02 | 5.84±0.04 | 5.96±0.03 | 6.04±0.09 | 6.04±0.09 | 0.01 |
| HbA1c, (%) | 5.62±0.01 | 5.56±0.02 | 5.64±0.02 | 5.70±0.05 | 5.70±0.04 | < 0.001 |
| eGFR | 94.89±0.45 | 97.19±0.61 | 94.06±0.47 | 91.54±0.95 | 92.65±0.85 | < 0.001 |
| Uric acid, (umol/L) | 324.43±1.24 | 318.82±2.05 | 328.97±1.72 | 327.93±3.19 | 321.39±3.42 | < 0.001 |
| TG, (mmol/L) | 2.73±0.03 | 2.64±0.05 | 2.73±0.05 | 2.89±0.12 | 2.96±0.10 | 0.03 |
| Total cholesterol, (mmol/L) | 5.02±0.02 | 5.04±0.02 | 5.02±0.02 | 4.96±0.05 | 4.95±0.05 | 0.23 |
| HDL, (mmol/L) | 1.38±0.01 | 1.43±0.01 | 1.36±0.01 | 1.32±0.02 | 1.31±0.02 | < 0.001 |
| LDL, (mmol/L) | 2.42±0.01 | 2.43±0.03 | 2.44±0.02 | 2.34±0.04 | 2.32±0.04 | 0.02 |
| TSH, (mIU/L) | 1.95±0.04 | 1.98±0.10 | 1.91±0.06 | 1.98±0.04 | 1.91±0.06 | 0.661 |
| FT4, (ug/dL) | 7.98±0.03 | 8.00±0.09 | 8.00±0.04 | 7.96±0.04 | 7.99±0.07 | 0.824 |
| SBP, (mmHg) | 121.8±0.3 | 121.3±0.4 | 121.9±0.4 | 122.6±0.6 | 122.4±0.7 | 0.42 |
| DBP, (mmHg) | 70.98±0.22 | 71.56±0.32 | 70.62±0.24 | 70.26±0.60 | 71.01±0.45 | 0.02 |
| Cancer, (%) | 0.001 | |||||
| No | 10401(90.1) | 3754(91.6) | 4928(89.5) | 723(85.5) | 996(89.2) | |
| Yes | 1144(9.9) | 310 (8.4) | 579(10.5) | 112(14.5) | 143(10.8) | |
| Thyroid disease, (%) | 0.002 | |||||
| No | 10329(89.5) | 3711(90.0) | 4915(88.9) | 729(86.5) | 974(85.2) | |
| Yes | 1216(10.5) | 353(10.0) | 592(11.1) | 106(13.5) | 165(14.8) |
UIC, urinary iodine concentration. MetS, metabolic syndrome; HbA1c, eGFR, Glomerular filtration rate; TG, triglyceride; HDL, high-density lipoprotein;
LDL, low-density lipoprotein; SBP, Systolic blood pressure; DBP, Diastolic blood pressure;
Data are presented as means (standard error), or weighted percentages as appropriate for the variable. Demographic and biochemical characteristics of the study population for Continuous normal variables were expressed as weighted mean ± standard deviation, One-way ANOVA was used to compare differences between groups. Categorical variables were expressed as frequencies and percentages and compared using Rao Scott’s χ2 test.