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Abstract
The present study reviewed the effects of excess iodine intake on thyroid function and the incidence of thyroid disease and discussed the scientific basis for establishing a tolerable upper intake level (UL) of iodine for Koreans. ULs are defined as “the highest level of daily nutrient intake that is likely to pose no risk of adverse effects to almost all individuals in the general population.” Koreans consume excess iodine from seaweed, and iodine intake is strongly influenced by seaweed consumption. However, no dose-response data derived from subjects consuming excess iodine frequently but not continuously during a lifetime are available. Therefore, the Korean DRI committee set the iodine UL to reduce the risk of adverse health effects by excess iodine intake for Koreans with distinctive seaweed-eating habits.
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Table 1.
Urinary iodine excretion of Korean normal adults and patients with thyroid disease
| References | Sample | Subjects (n) | Urinary iodine excretion 1) | |
|---|---|---|---|---|
| Mean | Range | |||
| Kim et al. 26) | 24 hr urine | Normal (245) | 3.52 ± 02.28 2) mg/d | 0.17-10.37 mg/d |
| Grave’s disease (27) | 5.33 ± 06.28 mg/d∗ | 0.92-29.21 mg/d | ||
| Primary hypothyroidism (7) | 1.07 ± 00.22 mg/d∗ | 0.79-01.51 mg/d | ||
| Cho et al. 44) | Spot urine | Normal (67) | 0.64 ± 00.06 mg/Lns | - 3) 0.23-01.25 mg/L |
| Simple goiter (39) | 0.55 ± 00.09 mg/L | - 0.18-00.89 mg/L | ||
| Hyperthyroidism (37) | 0.88 ± 00.21 mg/L | - 0.32-01.30 mg/L | ||
| Hypothyroidism (20) | 0.56 ± 00.12 mg/L | - 0.16-01.00 mg/L | ||
| Park et al. 45) | Spot urine | Normal (184) | 3.80 ±0 2.7 mg/L | 0.10-15.0 mg/L |
| Thyroid nodule (53) | 2.80 ± 02.7 mg/L | 0.10-09.0 mg/L | ||
| Hyperthyroidism (62) | 4.70 ± 10.8 mg/L | 0.10-066.0 mg/L | ||
| Chronic thyroiditis (42) | 3.20 ± 02.6 mg/L | 0.30-08.8 mg/L | ||
| Kim et al. 60) | 24hr urine or spot urine | Normal (40) | 1.13 ± 00.65 mg/d4) | -3) |
| (0.67 ± 00.38 mg/creatinine/d) | ||||
| Kim & Kim 67) | 24 hr urine | Normal (207) | 2.11 ± 00.69 mg/L | 0.70-05.04 mg/L |
| Simple goiter (17) | 2.88 ± 01.69 mg/L | 1.26-06.43 mg/L | ||
| Hyperthyroidism (42) | 4.90 ± 07.48 mg/L∗ | 1.01-34.9 mg/L | ||
| Hypothyroidism (15) | 4.57 ± 03.97 mg/L∗ | 1.17-12.75 mg/L | ||
| Thyroid cancer (11) | 6.18 ± 04.77 mg/L∗∗ | 1.10-14.35 mg/L | ||
Table 2.
Derivation of Tolerable Upper Intake Levels (UL) of iodine for Koreans
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