A Practical Approach for the Verification and Determination of Site- and Trimester-Specific Reference Intervals for Thyroid Function Tests in Pregnancy

AbstractThyroid function tests are frequently assessed during pregnancy to evaluate thyroid dysfunction or to monitor pre-existing thyroid disease. However, using non-pregnant reference intervals can lead to misclassification. International guidelines recommended that institutions should calculate their own pregnancy-specific reference intervals for free thyroxine (FT4), free triiodothyronine (FT3) and thyroid-stimulating hormone (TSH). The objective of this study is to establish gestation-specific reference intervals (GRIs) for thyroid function tests in pregnant Turkish women and to compare these with the age-matched non-pregnant women.Serum samples were collected from 220 non-pregnant women (age: 18–48), and 2460 pregnant women (age: 18–45) with 945 (39%) in the first trimester, 1120 (45%) in the second trimester, and 395 (16%) in the third trimester. TSH, FT4 and FT3 were measured using the Abbott Architect i2000SR analyzer.GRIs of TSH, FT4 and FT3 for first trimester pregnancies were 0.49–2.33 mIU/L, 10.30–18.11 pmol/L and 3.80–5.81 pmol/L, respectively. GRIs for second trimester pregnancies were 0.51–3.44 mIU/L, 10.30–18.15 pmol/L and 3.69–5.90 pmol/L. GRIs for third trimester pregnancies were 0.58–4.31 mIU/L, 10.30–17.89 pmol/L and 3.67–5.81 pmol/L. GRIs for TSH, FT4 and FT3 were different from non-pregnant normal reference intervals.TSH levels showed an increasing trend from the first trimester to the third trimester, whereas both FT4 and FT3 levels were uniform throughout gestation. GRIs may help in the diagnosis and appropriate management of thyroid dysfunction during pregnancy which will prevent both maternal and fetal complications.

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A study to establish gestation-specific reference intervals for thyroid function tests in normal singleton pregnancy

Yearbook of Pathology and Laboratory Medicine ◽

10.1016/s1077-9108(08)79068-6 ◽

2009 ◽

Vol 2009 ◽

pp. 245

Author(s):

M.G. Bissell

Keyword(s):

Thyroid Function ◽

Reference Intervals ◽

Specific Reference ◽

Thyroid Function Tests ◽

Singleton Pregnancy ◽

Function Tests

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Trimester-specific reference intervals of thyroid function tests in Turkish pregnants

Gynecological Endocrinology ◽

10.1080/09513590.2019.1666817 ◽

2019 ◽

Vol 36 (5) ◽

pp. 413-416

Author(s):

Oktay Bulur ◽

Zeliha Atak ◽

Derun Taner Ertugrul ◽

Esin Beyan ◽

Emre Gunakan ◽

...

Keyword(s):

Thyroid Function ◽

Reference Intervals ◽

Specific Reference ◽

Thyroid Function Tests ◽

Function Tests

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A study to establish gestation-specific reference intervals for thyroid function tests in normal singleton pregnancy

European Journal of Obstetrics & Gynecology and Reproductive Biology ◽

10.1016/j.ejogrb.2007.10.007 ◽

2008 ◽

Vol 137 (1) ◽

pp. 61-66 ◽

Cited By ~ 33

Author(s):

Christina Cotzias ◽

Sarah-Jane Wong ◽

Erica Taylor ◽

Paul Seed ◽

Joanna Girling

Keyword(s):

Thyroid Function ◽

Reference Intervals ◽

Specific Reference ◽

Thyroid Function Tests ◽

Singleton Pregnancy ◽

Function Tests

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First- and Second-Trimester Reference Intervals for Thyroid Function Testing in a US Population

American Journal of Clinical Pathology ◽

10.1093/ajcp/aqaa165 ◽

2020 ◽

Author(s):

Dustin R Bunch ◽

Kyle Firmender ◽

Roa Harb ◽

Joe M El-Khoury

Keyword(s):

Thyroid Function ◽

The United States ◽

Reference Intervals ◽

Adverse Outcomes ◽

Specific Reference ◽

Thyroid Peroxidase ◽

Thyroid Function Tests ◽

Second Trimester ◽

Function Tests ◽

Increased Risk

Abstract Objectives Thyroid dysfunction in pregnancy is associated with increased risk of adverse outcomes to mother and child. Trimester-specific reference intervals for thyroid function tests are not routinely provided by clinical laboratories. In this study, we present first- and second-trimester-specific reference intervals in a US population for thyroid-stimulating hormone (TSH), free thyroxine (FT4), total thyroxine (T4), and total triiodothyronine (T3) measured on Roche analyzers. Methods We used patient samples from first- and second-trimester prenatal screening. Samples were limited to singleton pregnancies and negative screening results for thyroid peroxidase and thyroglobulin antibodies. Analytes (TSH, FT4, T4, and T3) were measured on a Roche Modular e170 then verified on a Roche cobas e801. Results The reference intervals established on the e170 and verified on the e801 for the first trimester were 0.11 to 3.48 mIU/L for TSH, 11.2 to 19.0 pmol/L for FT4, 51.1 to 185.6 nmol/L for T4, and 1.4 to 3.5 nmol/L for T3. The reference intervals for the second trimester were 0.31 to 3.85 mIU/L for TSH, 9.4 to 16.5 pmol/L for FT4, 55.1 to 174.0 nmol/L for T4, and 1.5 to 3.7 nmol/L for T3. Conclusions This is the first report of trimester-specific reference intervals for thyroid function tests on Roche analyzers in the United States, and it is consistent with worldwide reports.

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Changes of Thyroid Function Tests in Pregnancy and Contribution of Trimester Specific Reference Ranges to Diagnosis

Turkiye Klinikleri Journal of Medical Sciences ◽

10.5336/medsci.2014-41908 ◽

2015 ◽

Vol 35 (1) ◽

pp. 43-48

Author(s):

Özlem ÇAKIR MADENCİ ◽

Nihal YÜCEL ◽

Lale KÖROĞLU DAĞDELEN ◽

Gülşen MUTLUOĞLU ◽

Hasan Emin KAYA ◽

...

Keyword(s):

Thyroid Function ◽

Specific Reference ◽

Reference Ranges ◽

Thyroid Function Tests ◽

Function Tests ◽

In Pregnancy

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Hepatic Steatosis and Thyroid Function Tests in Overweight and Obese Children

International Journal of Endocrinology ◽

10.1155/2013/381014 ◽

2013 ◽

Vol 2013 ◽

pp. 1-8 ◽

Cited By ~ 19

Author(s):

L. Pacifico ◽

E. Bonci ◽

F. Ferraro ◽

G. Andreoli ◽

S. Bascetta ◽

...

Keyword(s):

Hepatic Steatosis ◽

Thyroid Function ◽

Visceral Obesity ◽

Reference Intervals ◽

Thyroid Function Tests ◽

Obese Children ◽

Serum Samples ◽

Nonalcoholic Fatty Liver ◽

Function Tests

Objectives. Associations between thyroid function and nonalcoholic fatty liver disease (NAFLD) are unknown in childhood. Thus, the aim of the present study was to investigate in 402 consecutive overweight/obese children the association between thyroid function tests and hepatic steatosis as well as metabolic variables.Methods. Hepatic steatosis was diagnosed by ultrasound after exclusion of infectious and metabolic disorders. Fasting serum samples were taken for determination of thyroid function (TSH, FT4, and FT3), along with alanine aminotransferase (ALT), lipid profile, glucose, insulin, and insulin resistance (IR).Results. Eighty-eight children (21.9%) had TSH above the normal range (>4.0 mIU/L). FT3 and FT4 were within the reference intervals in all subjects. Elevated TSH was associated with increased odds of having hepatic steatosis (OR 2.10 (95% CI, 1.22–3.60)), hepatic steatosis with elevated ALT (2.42 (95% CI, 1.29–4.51)), hypertriglyceridemia, elevated total cholesterol, and IR as well as metabolic syndrome (considered as a single clinical entity), after adjustment for age, gender, pubertal status, and body mass index-SD score (or waist circumference).Conclusions. In overweight/obese children, elevated TSH concentration is a significant predictor of hepatic steatosis and lipid and glucose dysmetabolism, independently of the degree of total and visceral obesity.

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Trimester-Specific Reference Ranges for Thyroid Hormones in Iranian Pregnant Women

Journal of Thyroid Research ◽

10.1155/2013/651517 ◽

2013 ◽

Vol 2013 ◽

pp. 1-6 ◽

Cited By ~ 11

Author(s):

Ladan Mehran ◽

Atieh Amouzegar ◽

Hossein Delshad ◽

Sahar Askari ◽

Mehdi Hedayati ◽

...

Keyword(s):

Thyroid Hormones ◽

Pregnant Women ◽

Thyroid Function ◽

Final Analysis ◽

Reference Intervals ◽

Specific Reference ◽

Reference Ranges ◽

Thyroid Function Tests ◽

Thyroid Disorder ◽

Function Tests

Background. Due to many physiological changes during pregnancy, interpretation of thyroid function tests needs trimester-specific reference intervals for a specific population. There is no normative data documented for thyroid hormones on healthy pregnant women in Iran. The present survey was conducted to determine trimester-specific reference ranges for serum TSH, thyroxine (TT4), and triiodothyronine (TT3).Methods. The serum of 215 cases was analyzed for measurement of thyroid function tests by immunoassay method of which 152 iodine-sufficient pregnant women without thyroid autoantibodies and history of thyroid disorder or goiter were selected for final analysis. Reference intervals were defined as 5th and 95th percentiles.Results. Reference intervals in the first, second, and third trimesters were as follows: TSH (0.2–3.9, 0.5–4.1, and 0.6–4.1 mIU/l), TT4 (8.2–18.5, 10.1–20.6, and 9–19.4 μg/dl), and TT3 (137.8–278.3, 154.8–327.6, and 137–323.6 ng/dl), respectively. No correlation was found between TSH and TT4 or TT3. Significant correlation was found between TT4 and TT3 in all trimesters (r=0.35,P<0.001).Conclusion. The reference intervals of thyroid function tests in pregnant women differ among trimesters. Applying trimester-specific reference ranges of thyroid hormones is warranted in order to avoid misclassification of thyroid dysfunction during pregnancy.

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