Evaluation of Thyroid Function in Pregnant Women Using Automated Immunoassays.
INTRODUCTION: Automated free thyroxine (FT4) immunoassays are widely available, but professional guidelines discourage their use in pregnant women due to theoretical under-recoveries attributed to increased thyroid hormone binding capacity and instead advocate the use of total T4 (TT4) or free thyro...
| Publicado en: | Clinical Chemistry Vol. 67; no. 5; pp. 772 - 781 |
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| Autores principales: | , , , |
| Formato: | Journal Article |
| Publicado: |
Oxford University Press / USA
May2021
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| Acceso en línea: | Ver este registro en EBSCOhost |
| fields | @attributes: recordID: 1 pdfLink: plink: https://search.ebscohost.com/login.aspx?direct=true&db=ccm&AN=151182402&site=ehost-live header: @attributes: shortDbName: ccm uiTerm: 151182402 longDbName: CINAHL Complete uiTag: AN controlInfo: bkinfo: dissinfo: jinfo: jid: 00099147 10CS jtl: Clinical Chemistry issn: 00099147 maglogo: N pubinfo: dt: May2021 vid: 67 iid: 5 pid: 622 pub: Oxford University Press / USA artinfo: ui: 151182402 10.1093/clinchem/hvab009 151182402 ppf: 772 ppct: 9 formats: fmt: @attributes: type: P tig: atl: Evaluation of Thyroid Function in Pregnant Women Using Automated Immunoassays. aug: au: Geno, K. Aaron Reed, Matthew S. Cervinski, Mark A. Nerenz, Robert D. affil: Department of Pathology and Laboratory Medicine, Dartmouth-Hitchcock Health System, Lebanon, NH, USA sug: ab: INTRODUCTION: Automated free thyroxine (FT4) immunoassays are widely available, but professional guidelines discourage their use in pregnant women due to theoretical under-recoveries attributed to increased thyroid hormone binding capacity and instead advocate the use of total T4 (TT4) or free thyroxine index (FTI). The impact of this recommendation on the classification of thyroid status in apparently euthyroid pregnant patients was evaluated. METHODS: After excluding specimens with thyroid autoantibody concentrations above reference limits, thyroidstimulating hormone (TSH), FT4, TT4, and T-uptake were measured on the Roche CobasVR platform in remnant clinical specimens from at least 147 nonpregnant women of childbearing age and pregnant women at each trimester. Split-sample comparisons of FT4 as measured by the Cobas and equilibrium dialysis were performed. RESULTS: FT4 decreased with advancing gestational age by both immunoassay and equilibrium dialysis. TSH declined during the first trimester, remained constant in the second, and increased throughout the third, peaking just before delivery. Interpretation of TT4 concentrations using 1.5-times the nonpregnant reference interval classified 13.6% of first trimester specimens below the lower reference limit despite TSH concentrations within trimester-specific reference intervals. Five FTI results from 480 pregnant individuals (about 1.0%) fell outside the manufacturer's reference interval. CONCLUSIONS: Indirect FT4 immunoassay results interpreted in the context of trimester-specific reference intervals provide a practical and viable alternative to TT4 or FTI. Declining FT4 and increasing TSH concentrations near term suggest that declining FT4 is not an analytical artifact but represents a true physiological change in preparation for labor and delivery. pubtype: Academic Journal doctype: Journal Article ougenre: Article language: English refInfo: holdings: @attributes: islocal: N |
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