Thyroid function evaluation by different commercially available free thyroid hormone measurement kits in term pregnant women and their newborns

Roti, Elio; Gardini, E.; Minelli, Roberta; Bianconi, L.; Flisi, M.

doi:10.1007/bf03350244

Cited by 77 publications

(46 citation statements)

References 48 publications

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“…When TBG concentrations are abnormal, FT4 estimate tests are normally preferred over TT4 immunoassay measurements. However, current non-dialysis FT4 assays are binding-protein dependent and cannot be compared in absolute terms across methods [24,25]. Serum T4 and T3 detection methods have evolved through a variety of technologies since the 1950s.…”

Section: Discussionmentioning

confidence: 99%

Trimester-specific reference intervals for thyroxine and triiodothyronine in pregnancy in iodine-sufficient women using isotope dilution tandem mass spectrometry and immunoassays

Soldin

Hilakivi‐Clarke

Weiderpass

et al. 2004

Clinica Chimica Acta

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Background-Accurate assessment of the pregnant woman's thyroid status is critical, for both the initiation of thyroid hormone therapy and for the adjustment of thyroid hormone dose in those already receiving thyroid hormone. Trimester-specific intervals are especially important during pregnancy when thyroid insufficiency may be associated with adverse obstetric outcome and fetal neurodevelopmental deficits. We defined pregnancy-specific reference intervals for thyroxine (T4) and 3,5,3′-triiodothyronine (T3). We used a novel isotope dilution tandem mass spectrometry (LC/MS/MS) method, and compare these to reference intervals obtained by immunoassays (IAs) performed on the same samples.Methods-Concentrations of circulating T4 and T3 were measured simultaneously during first, second and third trimesters and postpartum in iodine-sufficient, healthy, singleton pregnancies using API-3000 LC/MS/MS with deuterium-labeled internal standard (L-thyroxine-d 2 ). Immunoassays were conducted on the same samples (T4 Dade Behring RxL, T3 DPCImmunolite).Results-Linear regression is reported for method comparisons; for T4, the slope decreased from r=0.900 in nonpregnant women to 0.802-0.820 during pregnancy. For T3, correlations between LC/MS/MS and immunoassays were weaker in all cases (r=0.407-0.574).Conclusion-In this longitudinal study, we established trimester-specific reference intervals for T4 and T3 by LC/MS/MS and compare these to intervals obtained by immunoassays.

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Section: Discussionmentioning

confidence: 99%

Trimester-specific reference intervals for thyroxine and triiodothyronine in pregnancy in iodine-sufficient women using isotope dilution tandem mass spectrometry and immunoassays

Soldin

Hilakivi‐Clarke

Weiderpass

et al. 2004

Clinica Chimica Acta

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“…In healthy pregnant women fT4 concentrations decrease at the second and third trimester [12]. This phenomenon was considered to be a result of changes in thyroxine-binding globulin and albumin concentrations [13,14] or of a true hypothyroxinaemia, possibly reflecting iodine deficiency [15]. Brucker et al reported in women with normal thyroid function a drop of both fT4 and fT3 levels after the first trimester of pregnancy, with no influence of iodine supplementation [16].…”

Section: Rycina 1 Zmiany Stężeń Jodu W Moczu Porannym Oraz Tsh Ft4 mentioning

confidence: 99%

Iodine supplementation during pregnancy of hypothyroid women treated with L-thyroxine neither influences neonatal TSH nor prevents decrease in maternal free thyroid hormone concentrations in second and third trimesters

Jastrzębska

Kochman

Bartoszewicz

et al. 2015

Endokrynologia Polska

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Iodine supplementation during pregnancy of hypothyroid women treated with L-thyroxine neither influences neonatal TSH nor prevents decrease in maternal free thyroid hormone concentrations in second and third trimesters Suplementacja jodowa u ciężarnych z niedoczynnością tarczycy leczonych L-tyroksyną nie wpływa na stężenia TSH noworodków ani nie zapobiega obniżeniu stężeń wolnych hormonów tarczycy u matek w drugim i trzecim trymestrze AbstractIntroduction: Pregnant women require about 250 μg of iodine daily. Hypothyroid women treated with L-thyroxine do not utilise iodine, and metabolism of L-thyroxine tablets is an additional source of iodine for their foetuses. The aim of the study was to evaluate the influence of iodine supplementation in hypothyroid pregnant women treated with L-thyroxine on neonate TSH concentration and maternal thyroid parameters. Material and methods: Ninety-two pregnant women with primary hypothyroidism on adequate thyroid hormone replacement were voluntarily divided into two groups: "thyroxine" (n = 38) treated with L-thyroxine only, and "thyroxine + iodine" (n = 54) treated additionally with 150 μg/day of iodine since 10 th gestational week. Primary outcomes were the maternal thyroid function tests (TSH, fT4, fT3) and neonatal TSH concentrations at the 3-4 th day of life. Urinary iodine concentration was measured at first and third trimester to compare iodine status in both groups. Results: Iodine supplementation significantly increased median urinary ioduria in the third trimester (from 95.15 μg/L to 151.50 μg/L), but did not prevent the decrease of maternal fT4 and fT3 concentrations in the second and third trimester. Median neonate TSH concentration in both groups was within normal range, but was 33% higher in the "thyroxine + iodine" than in the "thyroxine" group (1.91 mU/L vs. 1.34 mU/L). Moreover, 8.77% of newborns in the "thyroxine + iodine" group had TSH > 5 mIU/L. Conclusions: We did not find evidence for a positive influence of iodine supplementation on thyroid function of either hypothyroid pregnant women sufficiently treated with L-thyroxine or their neonates. (Endokrynol Pol 2016; 67 (4): 367-374)

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“…Albumin-dependent methods produce lower values (down to 50%) because serum albumin decreases in pregnant women (74,75) …”

Section: How Should Thyroid Function Tests Be Interpreted During Pregmentioning

confidence: 99%

Utilização dos testes de função tireoidiana na prática clínica

Carvalho

Perez

Ward

2013

Arq Bras Endocrinol Metab

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Laboratory tests are essential for the accurate diagnosis and cost-effective monitoring of thyroid dysfunction. Hormone levels can only confirm a diagnosis when there is a high level of clinical suspicion. For most patients, symptoms are nonspecific and subtle, so biochemical tests are necessary to identify the disorder. The purpose of this article is to critically analyze the use of standard thyroid function tests, which include measuring the levels of serum thyroid-stimulating hormone (TSH), thyroid hormones and antithyroid antibodies. The pitfalls of and impediments to the routine use of these tests are discussed based on a Medline database survey, and recommendations are presented to optimize the use of these diagnostic tools in clinical practice. RESUMOExames laboratoriais são fundamentais para o diagnóstico acurado e o monitoramento custo--efetivo das disfunções tireoidianas. Quando há alta suspeita clínica, as dosagens hormonais apenas confirmam o diagnóstico. No entanto, na maioria dos pacientes, a sintomatologia é sutil e inespecífica, de forma que apenas testes bioquímicos podem detectar o transtorno. O objetivo deste artigo é fazer uma análise crítica do uso apropriado dos principais testes de função tireoidiana, entre eles a dosagem sérica do hormônio estimulante da tireoide (TSH), dos hormônios tireoidianos e dos anticorpos antitireoidianos. Mediante um levantamento na base de dados do Medline, são discutidas as principais armadilhas e interferências relacionadas ao uso cotidiano desses testes e são apresentadas recomendações para otimizar a utilização dessas ferramentas diagnósticas na prática clínica. Arq Bras Endocrinol Metab. 2013;57(3):193-204

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Thyroid function evaluation by different commercially available free thyroid hormone measurement kits in term pregnant women and their newborns

Cited by 77 publications

References 48 publications

Trimester-specific reference intervals for thyroxine and triiodothyronine in pregnancy in iodine-sufficient women using isotope dilution tandem mass spectrometry and immunoassays

Trimester-specific reference intervals for thyroxine and triiodothyronine in pregnancy in iodine-sufficient women using isotope dilution tandem mass spectrometry and immunoassays

Iodine supplementation during pregnancy of hypothyroid women treated with L-thyroxine neither influences neonatal TSH nor prevents decrease in maternal free thyroid hormone concentrations in second and third trimesters

Utilização dos testes de função tireoidiana na prática clínica

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