Journal of Nutrition and Health

  • 제55권2호
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  • Pages.250-262
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  • 2022
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  • 2288-3886(pISSN)
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  • 2288-3959(eISSN)
한국영양학회 (The Korean Nutrition Society)
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Effect of iodine restriction on short-term changes in thyroid function in patients with subclinical hypothyroidism

  • Kwon, Obin (Department of Biochemistry and Molecular Biology, Seoul National University College of Medicine) ;
  • Shin, Dong Yeob (Division of Endocrinology and Metabolism, Department of Internal Medicine, Yonsei University College of Medicine) ;
  • Lee, Eun Jig (Division of Endocrinology and Metabolism, Department of Internal Medicine, Yonsei University College of Medicine)
  • 투고 : 2022.03.08
  • 심사 : 2022.03.24
  • 발행 : 2022.04.30
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초록

Purpose: Elevated iodine intake is related to a higher prevalence of subclinical hypothyroidism (SCH). We investigated the short-term effect of dietary iodine restriction on thyroid function in patients with SCH with high iodine intakes. Methods: The iodine levels in 64 SCH patients with serum TSH levels from 4.0 to 10.0 mIU/L and normal serum fT4 levels (n = 64) were assessed using 24-hour urine iodine test results and iodine intake levels calculated using a semi-quantitative food frequency questionnaire. Dietary iodine restriction was not recommended for patients with an iodine intake in the normal range (group A, n = 13), but seaweed restriction was recommended for patients with high iodine intakes (group B, n = 33). Thyroid functions and iodine levels were rechecked after three months. Another eighteen patients were prescribed thyroid hormone replacement therapy according to clinical criteria. Results: Median baseline iodine intake for the 64 patients was 290.61 ㎍/day, and median 24-hour urine iodine was 33.65 µmol/g of creatinine. The major source of dietary iodine was seaweed, which accounted for 72.2% of median baseline intake. Urine iodine and calculated iodine intake levels were positively correlated with serum TSH levels (p < 0.001 and p = 0.027, respectively), and calculated iodine intakes were significantly correlated with urine iodine levels (p = 0.001). In group B, iodine restriction significantly decreased urine iodine (p = 0.042) and TSH levels (p = 0.004), and conversion to euthyroid status was achieved in 16 of the 33 patients (48.5%). Conclusion: Iodine intake and urine iodine levels are correlated with thyroid function in SCH patients, and dietary iodine restriction can aid functional thyroid recovery in patients with elevated iodine intakes.

키워드

과제정보

We are grateful to Dr. Jae Eun Shim (Daejeon University) and Dr. Jihyun Yoon (Seoul National University) for their constructive critique on the manuscript.

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