Free thyroxine reference interval in each trimester of pregnancy determined with the Roche Modular E-170 electrochemiluminescent immunoassay.

Full Abstract

OBJECTIVE:
To determine using a simplified study design trimester-specific FT4 reference intervals in pregnancy with the Roche Modular immunoassay in routine use.

DESIGN AND METHODS:
Surplus blood from 300 women in each trimester, drawn at documented times in the gestation, and from 40 age-matched nonpregnant women were assayed for FT4, thyroid stimulating hormone (TSH) and antithyroid peroxidase autoantibody (anti-TPO).

RESULTS:
After excluding women positive for anti-TPO and with abnormal TSH, reference intervals were calculated as 12.5-19.1 pmol/L (nonpregnant group), 11-19 pmol/L (first trimester), 9.7-17.5 pmol/L (second trimester) and 8.1-15.3 pmol/L (third trimester). 3rd trimester FT4 was significantly lower than that of the second trimester (p<0.001) which, in turn, was lower than that of the first trimester (p<0.001). FT4 reference intervals in pregnancy were significantly lower than in the nonpregnant women (p<0.002).

CONCLUSIONS:
The observed trimester-specific FT4 reference intervals progressively decline with advancing gestation and differ significantly from one another.

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Author information

Author/s: Gong, Yanping (Y); Hoffman, Barry R (BR);

Affiliation: Department of Laboratory Medicine and Pathobiology, University of Toronto, Canada.

Journal and publication information

Publication Type: Journal Article

Journal: Clinical biochemistry (Clin Biochem), published in United States. (Language: eng)

Reference: 2008-Jul; vol 41 (issue 10-11) : pp 902-6

Dates: Created 2008/06/16; Completed 2008/08/06;

PMID: 18457669, status: MEDLINE (last retrieval date: 11/6/2008)

Sourced from the National Library of Medicine. Abstract text and other information may be subject to copyright.

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MeSH headings (categories)

This article was linked to the MESH Headings shown below.

Female
Humans
Iodide Peroxidase - blood
Pregnancy - blood
Pregnancy Trimester, First

Associated Chemicals: Thyroxine (7488-70-2) ; Thyrotropin (9002-71-5) ; Iodide Peroxidase (EC 1.11.1.8)

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