Free T4 immunoassays are flawed during pregnancy

Lee, Richard H.; Spencer, Carole A.; Mestman, Jorge H.; Miller, Erin; Petrović, Ivana; Braverman, Lewis E.; Goodwin, T. Murphy

doi:10.1016/j.ajog.2008.10.042

Cited by 238 publications

(159 citation statements)

References 13 publications

Supporting

Mentioning

143

Contrasting

Unclassified

Order By: Relevance

“…The automated free T 4 and free T 3 assays used by routine laboratories do not separate the free fraction before analyses, and the estimates they give are prone to deviation from 'true free hormones' in many situations (38). One problem with these assays, when used in pregnancy, is the great variability in results obtained with assays from different manufacturers (39), which has led some experts to recommend not using these assays to diagnose and control thyroid disease in pregnancy (40).…”

Section: Changes In Thyroid Function and Test Reference Limits In Prementioning

confidence: 99%

ENDOCRINOLOGY IN PREGNANCY: Pregnancy and the incidence, diagnosing and therapy of Graves’ disease

Laurberg

Andersen

2016

European Journal of Endocrinology

View full text Add to dashboard Cite

Thyroid hormones are essential developmental factors, and Graves' disease (GD) may severely complicate a pregnancy. This review describes how pregnancy changes the risk of developing GD, how early pregnancy by several mechanisms leads to considerable changes in the results of the thyroid function tests used to diagnose hyperthyroidism, and how these changes may complicate the diagnosing of GD. Standard therapy of GD in pregnancy is anti-thyroid drugs. However, new studies have shown considerable risk of birth defects if these drugs are used in specific weeks of early pregnancy, and this should be taken into consideration when planning therapy and control of women who may in the future become pregnant. Early pregnancy is a period of major focus in GD, where pregnancy should be diagnosed as soon as possible, and where important and instant change in therapy may be warranted. Such change may be an immediate stop of anti-thyroid drug therapy in patients with a low risk of rapid relapse of hyperthyroidism, or it may be an immediate shift from methimazole/carbimazole (with risk of severe birth defects) to propylthiouracil (with less risk), or maybe to other types of therapy where no risk of birth defects have been observed. In the second half of pregnancy, an important concern is that not only the mother with GD but also her foetus should have normal thyroid function.Thyroid hormones are essential developmental factors as first shown by Gudernatsch when he, in 1912, fed tadpoles thyroid tissue and observed metamorphosis (1). In mammals, thyroid hormones are especially of importance for brain development (2, 3), and even a few months with lack of thyroid hormones in infant life may lead to irreversible brain damage. This is the background for the universal screening for congenital hypothyroidism performed in many countries. However, thyroid hormones are also important for normal pregnancy, and maternal thyroid disease may severely increase the risk of pregnancy complications, including Invited author's profile Peter Laurberg was Clinical Professor of Internal Medicine and Endocrinology, Department of Endocrinology, Aalborg University Hospital, Aalborg, Denmark. His research mainly focused on thyroid disease prevention, epidemiology, diagnosing and therapy, including studies on iodine and thyroid, and pregnancy and thyroid. He had special research interest on the risk from and optimal management of autoimmune hypo-and hyperthyroidism in pregnancy and post-partum, management of Graves' disease in general, and how the burden of thyroid disease can be minimized by adjusting the population's iodine intake. He has coauthored several international guidelines on thyroid disease management, including management of thyrotoxicosis, and thyroid disease in pregnancy. Peter Laurberg died June 20, 2016.

show abstract

Section: Changes In Thyroid Function and Test Reference Limits In Prementioning

confidence: 99%

ENDOCRINOLOGY IN PREGNANCY: Pregnancy and the incidence, diagnosing and therapy of Graves’ disease

Laurberg

Andersen

2016

European Journal of Endocrinology

View full text Add to dashboard Cite

show abstract

“…The determination of free thyroxin (FT4), biologically active hormone which is available to the organism of a pregnant woman (as well as to the foetus), is not affected by the concentration of binding proteins (75) , which are changed during pregnancy. Its concentration during pregnancy is partly affected both by the infl ow of iodine and the duration of the pregnancy.…”

Section: Thyroid Diseases In Pregnancy -Possibilities For Screeningmentioning

confidence: 99%

Recommendations on prenatal screening and the connections to other diseases such as thyroid dysfunction

Springer

Potluková²,

Límanová³

et al. 2012

Clinical Chemistry and Laboratory Medicine (CCLM)

View full text Add to dashboard Cite

The aim of general maternal-foetal care is to ensure an uncomplicated birth of a healthy baby to a healthy mother. There is a large range of screening tests used during pregnancy: for gestational diabetes, infection, rhesus-D status, thyroid dysfunction, as well as other tests. An important part of prenatal care is the screening of major aneuploidies, primarily for Down ' s syndrome. This screening is possible in either the fi rst or second trimester, or in both. Management of this type of screening is very similar around the world. Hypothyroidism can affect the psychomotor development of the child. Thyroidstimulating hormone (TSH), autoantibodies against thyroperoxidase (TPOAb), and free thyroxin (FT4) were determined within our group of 7530 pregnant women. Elevated concentrations of TSH were found in 5.1 % , suppression was found in 2.9 % and 11.5 % were TPOAb positive. Either a familial or personal history of thyroid or autoimmune diseases was present in 58.3 % of those women who tested positive on any thyroid test. At minimum, 40 % of women TPOAb positive during pregnancy have some kind of thyroid disorders after delivery. These results support the effi cacy of general thyroid function screening in early pregnancy, as well as the follow-up after delivery of those women who are positive.

show abstract

“…During the first trimester, TSH levels remained stable, instead of decreasing as usual during pregnancy (22), and FT 4 decreased at 12 WG, prompting L-T 4 therapy in a dose of 75 mg/day (0.6 mg/kg per day). With this dose, FT 4 increased to the lower limit of the normal range by 20 WG but decreased again by 24 WG.…”

Section: Maternal Thyroid Function and Treatment During Pregnancymentioning

confidence: 94%

Pregnancy in women heterozygous for MCT8 mutations: risk of maternal hypothyroxinemia and fetal care

Ramos

Morandini

Carré

et al. 2011

European Journal of Endocrinology

View full text Add to dashboard Cite

Context: Monocarboxylate transporter 8 (MCT8 or SLC16A2) mutations cause X-linked AllanHerndon-Dudley syndrome. Heterozygous females are usually asymptomatic, but pregnancy may modify thyroid function and MCT8 is expressed in the placenta, suggesting that maternal and fetal abnormalities might develop even in the absence of MCT8 fetal mutation. Genetic counseling is so far based on X-linked transmission, and prenatal diagnosis is rarely performed. Objective: To describe thyroid function and the prenatal diagnosis in pregnant mothers harboring heterozygous MCT8 mutations and management of the persistent maternal hypothyroxinemia. Patients: Two women heterozygous for MCT8 mutations (c.1690GOA and c.1393-1GOC) were monitored throughout pregnancy. Methods: Prenatal diagnosis included sex determination, direct MCT8 sequencing, and familial linkage analysis. Ultrasonography and hormonal assays for maternal thyroid function evaluation were performed serially during pregnancy. Neonatal thyroid hormonal status was assessed. Results: None of the three fetuses (two males and one female) carried MCT8 mutations. One of the two heterozygous mothers revealed gestational hypothyroxinemia, prompting early levothyroxine (L-T 4 ) therapy until delivery. The second heterozygous mother showed normal thyroid function but was preventively traited by L-T 4 and all of the three neonates had normal thyroid hormone levels and thyroid gland at birth, suggesting advantages of prenatal care and/or compensatory mechanisms. Conclusion: Heterozygous MCT8 women should be monitored for requirement of L-T 4 therapy to prevent fetal and neonatal hypothyroidism and to avoid risk of potential cognitive delay due to gestational hypothyroxinemia. Moreover, when the disease-causing mutation is known and/or the first child is affected, prenatal diagnosis for male fetuses should be assessed early for MCT8 mutations by direct sequencing.

show abstract

Free T4 immunoassays are flawed during pregnancy

Cited by 238 publications

References 13 publications

ENDOCRINOLOGY IN PREGNANCY: Pregnancy and the incidence, diagnosing and therapy of Graves’ disease

ENDOCRINOLOGY IN PREGNANCY: Pregnancy and the incidence, diagnosing and therapy of Graves’ disease

Recommendations on prenatal screening and the connections to other diseases such as thyroid dysfunction

Pregnancy in women heterozygous for MCT8 mutations: risk of maternal hypothyroxinemia and fetal care

Contact Info

Product

Resources

About