Table 1. Comparison of thyroid ultrasonographic findings, serum hormonal data, and urinary iodine concentrations between the two groups with and without prophylactic actions against thyroid exposure to radioiodine after the nuclear accident.
| Number of subjects | Prevalence of nodulea (%) | Preva-lence of solid nodule (%) | Preva-lence of cyst (%) | Total number of nodulesb , c | Number of solid nodulesc | Number of cystsc | The largest diameter of solid noduled (mm) | The largest diameter of cystd (mm) | Serum TSH (mIU/L)e | Serum fT3 (pmol/L)e | Serum fT4 (pmol/L)e | Serum Tg (µg/L)e | UIC (µg/L)f | |
| Group I | 303 | 74.1 | 4.1 | 72.5 | 2.5±1.6g | 0.06±0.33 | 2.4±1.6 | 5.1±3.1 | 2.5±1.0 | 2.0±1.0 (208)i | 6.3±0.7 (208) | 16.5±1.9 (208) | 22.4±21.2 (208) | 294 (414)h (232) |
| Group II | 834 | 72.4 | 4.2 | 70.9 | 2.4±1.7 | 0.05±0.23 | 2.4±1·7 | 5.2±3·0 | 2.6±1.1 | 2.0±1.1 (523) | 6.3±0.8 (523) | 16.4±1.9 (523) | 20.9±12·3 (523) | 262 (377) (538) |
Group I comprises the subjects who took potassium iodide (KI) after the nuclear accident, those who increased seaweed consumption following the accident, and those who did both.
Group II comprises the subjects except Group I.
Percentage of subjects who had solid nodules, cysts, or both.
The sum of the numbers of solid nodules and cysts in each subject.
The number was calculated including the subjects without solid nodule or cyst, who were considered to have a “zero” lesion.
The data were derived from only the subjects who had solid nodules (47 subjects) or cysts (811 subjects).
Serum hormonal data were derived from a total of 731 subjects.
UIC data were derived from a total of 770 subjects.
Mean ± S.D.
Median (IQR).
The numbers in parentheses indicate the number of subjects who contributed to the serum hormonal or UIC data in the respective groups.
Differences between the two groups were analyzed by Chi-square test (for the percentage data), pairwise t-test (for the mean ± S.D. data), or Kruskal-Wallis test [for the median (IQR) data].
There were no statistically significant differences in the thyroid ultrasonographic findings, serum hormonal data, and the UIC between the two groups.
TSH, thyroid-stimulating hormone; fT3, free triiodothyronine; fT4, free thyroxine; Tg, thyroglobulin; UIC, urinary iodine concentration.