Classification of maternal thyroid function in early pregnancy using repeated blood samples

2021 ◽  
Author(s):  
Louise Knøsgaard ◽  
Stig Andersen ◽  
Annebirthe Bo Hansen ◽  
Peter Vestergaard ◽  
Stine Linding Andersen
Keyword(s):  
Pregnant Women ◽  
Thyroid Function ◽  
Early Pregnancy ◽  
Specific Reference ◽  
Reference Ranges ◽  
Sample Median ◽  
Blood Samples ◽  
Reference Limit ◽  
Maternal Thyroid

Objective: The assessment of maternal thyroid function in early pregnancy is debated. It is well-established that pregnancy-specific reference ranges preferably should be used. We speculated if the use of repeated blood samples drawn in early pregnancy would influence the classification of maternal thyroid function. Design: Cohort study Methods: Pregnant women with repeated early pregnancy blood samples were identified in the North Denmark Region Pregnancy Cohort. Each sample was used for the measurement of TSH, free T4 (fT4), thyroid peroxidase antibodies (TPO-Ab), and thyroglobulin antibodies (Tg-Ab) (ADVIA Centaur XPT, Siemens Healthineers). Method- and pregnancy week-specific reference ranges were used for classification of maternal thyroid function. Results: Among 1,466 pregnancies included, 89 women had TSH above the upper reference limit in the first sample (median pregnancy week 8), and 44 (49.4%) of these similarly had high TSH in the second sample (median week 10). A total of 47 women had TSH below the lower reference limit in the first sample, and 19 (40.4 %) of these similarly had low TSH in the second sample. Regarding women classified with isolated changes in fT4 in the first sample, less than 20% were similarly classified as such in the second sample. The percentage agreement between the samples was dependent on the level of TSH in the first sample and the presence of TPO- and Tg-Ab. Conclusion: In a large cohort of pregnant women, the classification of maternal thyroid function varied considerably with the use of repeated blood samples. Results emphasize a focus on the severity of thyroid function abnormalities in pregnant women.

Classification of Thyroid Dysfunction in Pregnant Women Differs by Analytical Method and Type of Thyroid Function Test

2020 ◽  
Vol 105 (11) ◽  
Author(s):  
Stine Linding Andersen ◽  
Peter Astrup Christensen ◽  
Louise Knøsgaard ◽  
Stig Andersen ◽  
Aase Handberg ◽  
...  
Keyword(s):  
Thyroid Function ◽  
Analytical Method ◽  
Thyroid Dysfunction ◽  
Thyroid Function Test ◽  
Specific Reference ◽  
Reference Ranges ◽  
Free T4 ◽  
Function Test ◽  
Maternal Thyroid

Abstract Context Physiological alterations challenge the assessment of maternal thyroid function in pregnancy. It remains uncertain how the reference ranges vary by week of pregnancy, and how the classification of disease varies by analytical method and type of thyroid function test. Design Serum samples from Danish pregnant women (n = 6282) were used for the measurement of thyrotropin (TSH), total and free thyroxine (T4), total and free 3,5,3′-triiodothyronine (T3), and T-uptake using “Method A” (Cobas 8000, Roche Diagnostics). TSH and free T4 were also measured using “Method B” (ADVIA Centaur XP, Siemens Healthineers). Main Outcome Measures Pregnancy week- and method-specific reference ranges were established among thyroid antibody–negative women (n = 4612). The reference ranges were used to classify maternal thyroid function, and results were compared by analytical method and type of thyroid function test. Results The reference ranges for TSH showed a gradual decrease during pregnancy weeks 4 to 14, a gradual increase was observed for total T4, total T3, and T-uptake, whereas free T4 and free T3 showed less variation. When TSH and free T4 were used, Method A classified 935 (14.9%) with abnormal thyroid function, Method B a total of 903 (14.4%), and the methods agreed on 554 individuals. When TSH and total T4 were used, 947 (15.1%) were classified with abnormal thyroid function, and classifications by either total T4 or free T4 agreed on 584 individuals. Conclusions Even when pregnancy week- and method-specific reference ranges were established, the classification of maternal thyroid dysfunction varied considerably by analytical method and type of thyroid function test.

scholarly journals Reference Intervals of Thyroid Hormones and Correlation of BMI with Thyroid Function in Healthy Zhuang Ethnic Pregnant Women

2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
Yonghong Sheng ◽  
Dongping Huang ◽  
Shun Liu ◽  
Xuefeng Guo ◽  
Jiehua Chen ◽  
...  
Keyword(s):  
Thyroid Hormones ◽  
Pregnant Women ◽  
Thyroid Function ◽  
Reference Intervals ◽  
Thyroid Stimulating Hormone ◽  
Specific Reference ◽  
American Thyroid Association ◽  
Reference Ranges ◽  
Free Triiodothyronine ◽  
Cross Sectional

Ethnic differences in the level of thyroid hormones exist among individuals. The American Thyroid Association (ATA) recommends that an institution or region should establish a specific thyroid hormone reference value for each stage of pregnancy. To date, a limited number of studies have reported the level of thyroid hormones in Chinese minorities, and the exact relationship between BMI and thyroid function in pregnant women is ill. This study was performed to establish trimester-specific reference ranges of thyroid hormones in Zhuang ethnic pregnant women and explore the role of body mass index (BMI) on thyroid function. A total of 3324 Zhuang ethnic health pregnant women were recruited in this Zhuang population-based retrospective cross-sectional study. The values of thyroid stimulating hormone (TSH), free thyroxine (FT4), and free triiodothyronine (FT3) were determined by automatic chemiluminescence immunoassay analyzer. Multivariate linear regression and binary logistic regression were constructed to evaluate the influence of BMI on the thyroid function. The established reference intervals for the serum thyroid hormones in three trimesters were as follows: TSH, 0.02–3.28, 0.03–3.22, and 0.08-3.71 mIU/L; FT4, 10.57–19.76, 10.05–19.23, and 8.96–17.75 pmol/L; FT3, 3.51–5.64, 3.42–5.42, and 2.93–5.03 pmol/L. These values were markedly lower than those provided by the manufacturers for nonpregnant adults which can potentially result in 6.10% to 19.73% misclassification in Zhuang pregnant women. Moreover, BMI was positively correlated with isolated hypothyroxinemia (OR=1.081, 95% CI=1.007–1.161), while the correlation between the BMI and subclinical hypothyroidism was not statistically significant (OR=0.991, 95% CI=0.917–1.072). This is the first study focusing on the reference ranges of thyroid hormones in Guangxi Zhuang ethnic pregnant women, which will improve the care of them in the diagnosis and treatment. We also found that high BMI was positively associated with the risk of isolated hypothyroxinemia.

scholarly journals High Body Mass Index Is an Indicator of Maternal Hypothyroidism, Hypothyroxinemia, and Thyroid-Peroxidase Antibody Positivity during Early Pregnancy

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Cheng Han ◽  
Chenyan Li ◽  
Jinyuan Mao ◽  
Weiwei Wang ◽  
Xiaochen Xie ◽  
...  
Keyword(s):  
Body Mass Index ◽  
Pregnant Women ◽  
Body Mass ◽  
Thyroid Function ◽  
Early Pregnancy ◽  
Thyroid Dysfunction ◽  
Thyroid Peroxidase ◽  
Thyroid Peroxidase Antibody ◽  
Maternal Thyroid ◽  
High Bmi

Background. Maternal thyroid dysfunction in early pregnancy may increase the risk of adverse pregnancy complications and neurocognitive deficiencies in the developing fetus. Currently, some researchers demonstrated that body mass index (BMI) is associated with thyroid function in nonpregnant population. Hence, the American Thyroid Association recommended screening thyroid function in obese pregnant women; however, the evidence for this is weak. For this purpose, our study investigated the relationship between high BMI and thyroid functions during early pregnancy in Liaoning province, an iodine-sufficient region of China.Methods. Serum thyroid stimulating hormone (TSH), free thyroxine (FT4), thyroid-peroxidase antibody (TPOAb), thyroglobulin antibody (TgAb) concentration, urinary iodine concentration (UIC), and BMI were determined in 6303 pregnant women.Results. BMI ≥ 25 kg/m2may act as an indicator of hypothyroxinemia and TPOAb positivity and BMI ≥ 30 kg/m2was associated with increases in the odds of hypothyroidism, hypothyroxinemia, and TPOAb positivity. The prevalence of isolated hypothyroxinemia increased among pregnant women with BMI > 24 kg/m2.Conclusions. High BMI during early pregnancy may be an indicator of maternal thyroid dysfunction; for Asian women whose BMI > 24 kg/m2and who are within 8 weeks of pregnancy, thyroid functions should be assessed especially.

scholarly journals Evaluation of maternal thyroid function during pregnancy: the importance of using gestational age-specific reference intervals

2007 ◽  
Vol 157 (4) ◽  
pp. 509-514 ◽  
Author(s):  
Rt Stricker ◽  
M Echenard ◽  
R Eberhart ◽  
M-C Chevailler ◽  
V Perez ◽  
...  
Keyword(s):  
Pregnant Women ◽  
Thyroid Function ◽  
Gestational Age ◽  
Thyroid Disease ◽  
Thyroid Dysfunction ◽  
Reference Intervals ◽  
Specific Reference ◽  
Thyroid Function Tests ◽  
Laboratory Evidence ◽  
Maternal Thyroid

Background: Maternal thyroid dysfunction has been associated with a variety of adverse pregnancy outcomes. Laboratory measurement of thyroid function plays an important role in the assessment of maternal thyroid health. However, occult thyroid disease and physiologic changes associated with pregnancy can complicate interpretation of maternal thyroid function tests (TFTs). Objective and methods: To 1) establish the prevalence of laboratory evidence for autoimmune thyroid disease (AITD) in pregnant women; 2) establish gestational age-specific reference intervals for TFTs in women without AITD; and 3) examine the influence of reference intervals on the interpretation of TFT in pregnant women. Serum samples were collected from 2272 pregnant women, and TFT performed. Gestational age-specific reference intervals were determined in women without AITD, and then compared with the non-pregnant assay-specific reference intervals for interpretation of testing results. Results: Thyroid peroxidase antibodies (TPO-Ab) and thyroglobulin antibodies (Tg-Ab) were positive in 10.4 and 15.7% of women respectively. TPO-Ab level was related to maternal age, but TPO-Ab status, Tg-Ab status, and Tg-Ab level were not. Women with TSH > 3.0 mIU/l were significantly more likely to be TPO-Ab positive. Gestational age-specific reference intervals for TFT were significantly different from non-pregnant normal reference intervals. Interpretation of TFT in pregnant women using non-pregnant reference intervals could potentially result in misclassification of a significant percentage of results (range: 5.6–18.3%). Conclusion: Laboratory evidence for thyroid dysfunction was common in this population of pregnant women. Accurate classification of TFT in pregnant women requires the use of gestational age-specific reference intervals.

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

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
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.

TSH and fT4 during pregnancy: an observational study and a review of the literature

2016 ◽  
Vol 54 (7) ◽  
Author(s):  
Annemiek M.C.P. Joosen ◽  
Ivon J.M. van der Linden ◽  
Neletta de Jong-Aarts ◽  
Marieke A.A. Hermus ◽  
Antonius A.M. Ermens ◽  
...  
Keyword(s):  
Pregnant Women ◽  
Thyroid Function ◽  
Hyperemesis Gravidarum ◽  
Past History ◽  
Post Partum ◽  
Multiple Pregnancy ◽  
Reference Intervals ◽  
Specific Reference ◽  
Hormonal Stimulation ◽  
Reference Limit

AbstractTrimester-specific reference intervals for TSH are recommended to assess thyroid function during pregnancy due to changes in thyroid physiology. Laboratories should verify reference intervals for their population and assay used. No consistent upper reference limit (URL) for TSH during pregnancy is reported in literature. We investigated the use of non-pregnant reference intervals for TSH, recommended during pregnancy by current Dutch guidelines, by deriving trimester-specific reference intervals in disease-free Dutch pregnant women as these are not available.Apparently healthy low risk pregnant women were recruited via midwifery practices. Exclusion criteria included current or past history of thyroid or other endocrine disease, multiple pregnancy, use of medication known to influence thyroid function and current pregnancy as a result of hormonal stimulation. Women who were TPO-antibody positive, miscarried, developed hyperemesis gravidarum, hypertension, pre-eclampsia, HELLP, diabetes or other disease, delivered prematurely or had a small for gestational age neonate were excluded. Blood samples were collected at 9–13 weeks (n=99), 27–29 weeks (n=96) and 36–39 weeks (n=96) of gestation and at 4–13 weeks post-partum (n=95). Sixty women had complete data during pregnancy and post-partum. All analyses were performed on a Roche Cobas e601 analyser.In contrast to current Dutch guidelines, the 97.5th percentiles of TSH in the first (3.39 mIU/L) and second trimesters (3.38 mIU/L) are well under the non-pregnant URL of 4.0 mIU/L. The higher TSH in the third trimester (97.5th percentile 3.85 mIU/L) is close to the current non-pregnant URL of 4.0 mIU/L. Absolute intra-individual TSH is relatively stable during pregnancy and post-partum as individuals tracked within the tertile assigned in trimester 1. Even small deviations within the population reference interval may indicate subtle thyroid dysfunction.

scholarly journals A Novel Nomogram for Predicting the Risk of Premature Delivery Based on the Thyroid Function in Pregnant Women

2022 ◽  
Vol 12 ◽  
Author(s):  
Yu Meng ◽  
Jing Lin ◽  
Jianxia Fan
Keyword(s):  
Risk Factors ◽  
Pregnant Women ◽  
Preterm Delivery ◽  
Thyroid Function ◽  
Premature Delivery ◽  
Multivariable Logistic Regression Analysis ◽  
Decision Curve Analysis ◽  
Cutoff Values ◽  
Lemeshow Test ◽  
Maternal Thyroid

BackgroundMaternal thyroid dysfunction and autoantibodies were associated with preterm delivery. However, recommendations for cutoff values of thyroperoxidase antibody (TPOAb) positivity and thyroid-stimulating homone (TSH) associated with premature delivery are lacking.ObjectiveTo identify the pregnancy-specific cutoff values for TPOAb positivity and TSH associated with preterm delivery. To develop a nomogram for the risk prediction of premature delivery based on maternal thyroid function in singleton pregnant women without pre-pregnancy complications.MethodsThis study included data from the International Peace Maternity and Child Care Health Hospital (IPMCH) in Shanghai, China, between January 2013 and December 2016. Added data between September 2019 and November 2019 as the test cohort. Youden’s index calculated the pregnancy-specific cutoff values for TPOAb positivity and TSH concentration. Univariate and multivariable logistic regression analysis were used to screen the risk factors of premature delivery. The nomogram was developed according to the regression coefficient of relevant variables. Discrimination and calibration of the model were assessed using the C-index, Hosmer-Lemeshow test, calibration curve and decision curve analysis.Results45,467 pregnant women were divided into the training and validation cohorts according to the ratio of 7: 3. The testing cohort included 727 participants. The pregnancy-specific cutoff values associated with the risk of premature delivery during the first trimester were 5.14 IU/mL for TPOAb positivity and 1.33 mU/L for TSH concentration. Multivariable logistic regression analysis showed that maternal age, history of premature delivery, elevated TSH concentration and TPOAb positivity in the early pregnancy, preeclampsia and gestational diabetes mellitus were risk factors of premature delivery. The C-index was 0.62 of the nomogram. Hosmer-Lemeshow test showed that the Chi-square value was 2.64 (P = 0.955 &gt; 0.05). Decision curve analysis showed a positive net benefit. The calibration curves of three cohorts were shown to be in good agreement.ConclusionsWe identified the pregnancy-specific cutoff values for TPOAb positivity and TSH concentration associated with preterm delivery in singleton pregnant women without pre-pregnancy complications. We developed a nomogram to predict the occurrence of premature delivery based on thyroid function and other risk factors as a clinical decision-making tool.

scholarly journals Comparison of Maternal and Perinatal Outcome in Pregnant Women with Hypothyroidism Diagnosed before Conception with Hypothyroidism Diagnosed during Pregnancy

2014 ◽  
Vol 2 (2) ◽  
pp. 21-27
Author(s):  
P Basnet ◽  
N Aggrawal ◽  
V Suri ◽  
P Dutta ◽  
K Mukhopadhyay
Keyword(s):  
Birth Weight ◽  
Pregnant Women ◽  
Thyroid Function ◽  
Early Pregnancy ◽  
Perinatal Outcome ◽  
Fetal Outcome ◽  
Endocrine Disorder ◽  
Fetal Birth Weight ◽  
Group A ◽  
Group B

BACKGROUND: Thyroid disorder is one of commonest endocrine disorder in women and hence constitutes a common endocrine disorder complicating pregnancy. Diagnosing and treating hypothyroidism preconceptionally and during early pregnancy appears to be a useful strategy to improve maternal and fetal outcome. OBJECTIVE: To compare the maternal and perinatal outcome in pregnant women with hypothyroidism diagnosed preconceptionally with hypothyroidism diagnosed during pregnancy. METHODS: A prospective study. One hundred pregnant women with hypothyroidism at less than 20 weeks Period of Gestation (POG) were recruited for the study and grouped into two groups: Group A-hypothyroidism diagnosed and on treatment before conception, Group B-hypothyroidism diagnosed and started on treatment during pregnancy. Both groups were intensively monitored during pregnancy with serial Thyroid Function Test (TFT) and thyroxine replacement doses were adjusted accordingly. Various maternal, perinatal and fetal outcome measures were studied in both groups prospectively till delivery. RESULTS: The maternal and fetal complications were comparable in the two groups, however the fetal birth weight was significantly higher in Group A versus Group B (2.89±0.485kg vs. 2.70±0.453kg; p=0.039). All the new born babies had normal thyroid function. CONCLUSION: Hypothyroidism diagnosed preconceptionally or during early pregnancy and treated appropriately has beneficial effect on fetal birth weight, and hence the total pregnancy outcome. Screening for thyroid dysfunction should be judiciously performed in all high risk women prior to a planned conception or during their first antenatal visit. DOI: http://dx.doi.org/10.3126/jucms.v2i2.11170   Journal of Universal College of Medical Sciences (2014) Vol.2(2): 21-27

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