Korean J Intern Med.
2018 May;33(3):552-560. 10.3904/kjim.2016.051.
Reference intervals of thyroid hormones during pregnancy in Korea, an iodine-replete area
- Affiliations
-
- 1Division of Endocrinology and Metabolism, Department of Medicine, Thyroid Center, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
- 2Division of Endocrinology and Metabolism, Department of Internal Medicine, Soonchunhyang University Hospital Seoul, Seoul Korea.
- 3Division of Endocrinology and Metabolism, Department of Medicine, Gyeongsang National University School of Medicine, Jinju, Korea.
- 4Department of Medicine, Institute of Health Sciences, Gyeongsang National University School of Medicine, Jinju, Korea.
- 5Department of Medical Education, Sungkyunkwan University School of Medicine, Seoul, Korea.
- 6Department of Laboratory Medicine and Genetics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
- 7Department of Obstetrics and Gynecology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea. ohsymd.oh@samsung.com
- KMID: 2411583
- DOI: http://doi.org/10.3904/kjim.2016.051
Abstract
- BACKGROUND/AIMS
Maternal thyroid dysfunction has been associated with adverse pregnancy outcomes. The purpose of our study was to establish trimester-specific reference intervals for thyroid hormones in pregnant women in Korea, where iodine intake is more than adequate and to examine pregnancy and perinatal outcomes in their offspring.
METHODS
Among 459 healthy pregnant women who were screened, we enrolled 417 subjects who had negative results for thyroid autoantibodies. Serum thyroid stimulating hormone (TSH) and free thyroxine were measured using an immunoradiometric assay. Urine iodine concentration was measured using inductively coupled plasma-mass spectrometry in 275 women. Reference ranges of thyroid hormones were determined according to the guidelines of the National Academy of Clinical Biochemistry. Pregnancy and perinatal outcomes were compared according to maternal thyroid function.
RESULTS
The reference ranges of serum TSH were 0.03 to 4.24 mIU/L in the first trimester, 0.13 to 4.84 mIU/L in the second trimester, and 0.30 to 5.57 mIU/L in the third trimester. Pregnancy and perinatal outcomes did not vary in mothers with subtle changes in thyroid function.
CONCLUSIONS
Trimester-specific thyroid hormone reference intervals in Korean pregnant women differ from those of other countries with different iodine nutrition status and ethnicity. The establishment of population-based, reliable trimester-specific reference intervals is critical for the interpretation of thyroid function in pregnant women to avoid unnecessary tests and treatments.
MeSH Terms
-
Autoantibodies
Biochemistry
Female
Humans
Immunoradiometric Assay
Iodine
Korea*
Mothers
Nutritional Status
Pregnancy Outcome
Pregnancy Trimester, First
Pregnancy Trimester, Second
Pregnancy Trimester, Third
Pregnancy*
Pregnant Women
Reference Values
Republic of Korea
Spectrum Analysis
Thyroid Gland*
Thyroid Hormones*
Thyrotropin
Thyroxine
Autoantibodies
Iodine
Thyroid Hormones
Thyrotropin
Thyroxine
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