Reference intervals for thyroid hormones during the first trimester of gestation: A report from an area with a sufficient iodine level

KIANPOUR, Maryam, AMINORROAYA, Ashraf, AMINI, Massoud, FEIZI, Awat, JANGHORBANI, Mohsen, SHOKRI, Saeideh, AMINORROAYA YAMINI, Sima, FARGHADANI, Maryam, HEKMATNIA, Ali and GHARIB, Hossien (2019). Reference intervals for thyroid hormones during the first trimester of gestation: A report from an area with a sufficient iodine level. Hormone and metabolic research, 51 (03), 165-171.

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The physiological changes during pregnancy modulate the endocrine system. Therefore, both the American and the European thyroid associations recommend the use of local trimester-specific reference intervals. The purpose of this study was to establish the first trimester reference intervals for thyroid function tests in the central area of Iran. We examined 436 pregnant women in their first trimester of pregnancy, and 444 non-pregnant women in a cross sectional study. Serum levels of thyroid stimulating hormone (TSH), free thyroxin (FT4), free triiodothyronine (FT3), thyroid peroxidase antibody, urinary iodine concentration (UIC), and thyroid volume were measured for all subjects. The first trimester-specific reference intervals (2.5th–97.5th percentile) were determined for 185 pregnant women and 256 non-pregnant women with negative TPOAb, adequate iodine level (UIC≥150 μg/l in pregnant and UIC≥100 μg/l in non-pregnant women), and normal thyroid examination. We calculated multiples of the median (MoM) for TFTs to normalize the obtained data. The first trimester-specific reference intervals of serum TSH, FT4, and FT3 for pregnant women were 0.20–4.60 mIU/l, 9.0–18.02 pmol/l, and 3.40–5.64 pmol/l, respectively, while the corresponding figures for non-pregnant women were 0.59–5.60 mIU/l, 9.52–19.30 pmol/l, and 3.70–5.55 pmol/l, respectively. The first and 99th percentile MoM of TSH in pregnant women in their first-trimester was 0.06–4.62. The local normal reference ranges for the first trimester of pregnancy in central region of Iran were different from the ranges suggested by the ATA.

Item Type: Article
Additional Information: ** From Crossref via Jisc Publications Router **Journal IDs: pissn 0018-5043; eissn 1439-4286 **History: published_online 12-03-2019
Uncontrolled Keywords: Clinical Biochemistry, Biochemistry, Endocrinology, Diabetes and Metabolism, Endocrinology, Biochemistry, medical, General Medicine
Identification Number:
Page Range: 165-171
SWORD Depositor: Louise Beirne
Depositing User: Louise Beirne
Date Deposited: 21 Mar 2019 09:49
Last Modified: 18 Mar 2021 06:20

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