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Kim, Park, Kim, Ahn, Kim, Cho, Lee, Yoo, Kim, Seo, Kim, Choi, Baik, Choi, and Kim: Thyroid Dysfunction of North Korean Women Living in South Korea, Focusing on Subclinical Hypothyroidism
Original Article
Endocrinology and Metabolism

Endocrinology and Metabolism 2012; 27(3): 200-207.

Published online: 19 September 2012

DOI: https://doi.org/10.3803/EnM.2012.27.3.200

Thyroid Dysfunction of North Korean Women Living in South Korea, Focusing on Subclinical Hypothyroidism

Joo Hyung Kim, Sol Ah Park1, Nam Hoon Kim, Jae Hee Ahn, Yoon Jung Kim, Myongjin Cho2, Yoon Jung Lee3, Hye Jin Yoo, Hee Young Kim, Ji A Seo, Nan Hee Kim, Kyung Mook Choi, Sei Hyun Baik, Dong Seop Choi, Sin Gon Kim

Division of Endocrinology and Metabolism, Department of Internal Medicine, Korea University Medical Center, Korea University College of Medicine, Seoul, Korea.

1Korea University College of Medicine, Seoul, Korea.

2Department of Endocrinology, Cheju Halla General Hospital, Jeju, Korea.

3Division of Endocrinology and Metabolism, Department of Internal Medicine, Inje University Ilsan Paik Hospital, Inje University College of Medicine, Ilsan, Korea.

Corresponding author: Sin Gon Kim. Division of Endocrinology and Metabolism, Department of Internal Medicine, Korea University Anam Hospital, Korea University College of Medicine, 73 Inchon-ro, Seongbuk-gu, Seoul 136-705, Korea. Tel: +82-2-920-5890, Fax: +82-2-953-9355, k50367@korea.ac.kr

Received 4 May 2012       Accepted 27 July 2012

Copyright © 2012 Korean Endocrine Society

(open-access):

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Background

Thyroid function depends on ethnic and environmental factors. North Korean refugees have the same genetic background as South Koreans, but they have been exposed to different environments. This study examines the prevalence and pattern of thyroid disorders in North Korean women living in South Korea, focusing on subclinical hypothyroidism (SCH).

Methods

The intended sample was a total of 327 North Korean women residing in Seoul. Health questionnaires and medical examinations, including serum thyrotropin (thyroid stimulating hormone, TSH), free thyroxine, and thyroid autoantibodies, were conducted.

Results

The prevalence of SCH was 9.4%. In logistic regression analysis, smoking, menopause, length of stay in South Korea, body mass index, history of thyroid disease, and metabolic syndrome were not associated with the risk of SCH. Whereas, the positivity of autoantibodies were associated with a high risk for SCH (odds ratio [OR], 4.840; 95% confidence interval [CI], 1.80-13.017; P = 0.002), and age was associated with a low risk for SCH (OR, 0.94; 95% CI, 0.888-0.994; P = 0.031). The serum TSH levels also decreased with increasing age, and in particular, there was significant difference between 30-39 years, and over 60 years (2.33 ± 1.51 µIU/mL vs. 1.54 ± 0.73 µIU/mL, P = 0.028).

Conclusion

In North Korean women, the positivity of autoantibodies was associated with a high risk for SCH. But interestingly, a younger age was associated with a high risk for SCH. Considering that they suffered from severe famine at the period of growth, and this led to malnutrition, their thyroid dysfunction might be associated with the peculiar environment that they experienced.

Keywords: North Korean refugees, Subclinical hypothyroidism, Thyroid autoantibody

Figures and Tables

Fig. 1
Prevalence of subclinical hypothyroidism (SCH) and positivity of autoantibody according to age groups. The younger they are, the more prevalence of SCH was increased (P for trend = 0.011). But such trend was not seen in presence of autoantibody.
enm-27-200-g001
Fig. 2
Comparison of free T4 and thyroid stimulating hormone concentration according to age groups. The differences between groups were evaluated using one-way ANOVA with Bonferroni's post hoc test (thyroid stimulating hormone [TSH], 30-39 vs. 60-, 2.33 ± 1.51 vs. 1.54 ± 0.73, P = 0.028; free thyroxine [free T4], 30-39 vs. 40-49, 1.35 ± 0.18 vs. 1.28 ± 0.16, P = 0.021).
enm-27-200-g002
Table 1
Baseline characteristics of the study participants (n = 327)
enm-27-200-i001

Values are expressed as mean ± SD or percentage (n).

CES-D, Center for Epidemiological Studies-Depression Scale; PWI-SF, Psychosocial Well-Being Index-Short Form.

Table 2
Thyroid status of the study participants
enm-27-200-i002

Values are expressed as mean ± SD or percentage (n).

Free T4, free thyroxine; TSH, thyroid stimulating hormone.

Table 3
Comparison of characteristics between euthyroid and subclinical hypothyroid subjects
enm-27-200-i003

Values are expressed as median, mean ± SD or percentage (n).

CES-D, Center for Epidemiological Studies-Depression Scale; Free T4, free thyroxine; HDL-C, high density lipoprotein cholesterol; HOMA-IR, homeostatic model assessment for insulin resistance; LDL-C, low density lipoprotein cholesterol; PWI-SF, Psychosocial Well-Being Index-Short Form; SCH, subclinical hypothyroidism; TSH, thyroid stimulating hormone.

Table 4
Risk factors for subclinical hypothyroidism
enm-27-200-i004

ORs were calculated using binary logistic regression analysis.

CI, confidential interval; OR, odds ratio.

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