Method-dependent variation in TSH and FT4 reference intervals in pregnancy: A systematic review

Okosieme, Onyebuchi E, Agrawal, Medha, Usman, Danyal and Evans, Carol 2021. Method-dependent variation in TSH and FT4 reference intervals in pregnancy: A systematic review. Annals of Clinical Biochemistry 58 (5) , pp. 537-546. 10.1177/00045632211026955

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Abstract

Background Gestational TSH and FT4 reference intervals may differ according to assay method, but the extent of variation is unclear and has not been systematically evaluated. We conducted a systematic review of published studies on TSH and FT4 reference intervals in pregnancy. Our aim was to quantify method-related differences in gestation reference intervals, across four commonly used assay methods, Abbott, Beckman, Roche and Siemens. Methods We searched the literature for relevant studies, published between January 2000 and December 2020, in healthy pregnant women without thyroid antibodies or disease. For each study, we extracted trimester-specific reference intervals (2.5–97.5 percentiles) for TSH and FT4 as well as the manufacturer-provided reference interval for the corresponding non-pregnant population. Results TSH reference intervals showed a wide range of study-to-study differences with upper limits ranging from 2.33 to 8.30 mU/L. FT4 lower limits ranged from 4.40 to 13.93 pmol/L, with consistently lower reference intervals observed with the Beckman method. Differences between non-pregnant and first trimester reference intervals were highly variable, and for most studies, the TSH upper limit in the first trimester could not be predicted or extrapolated from non-pregnant values. Conclusions Our study confirms significant intra- and intermethod disparities in gestational thyroid hormone reference intervals. The relationship between pregnant and non-pregnant values is inconsistent and does not support the existing practice in many laboratories of extrapolating gestation references from non-pregnant values. Laboratories should invest in deriving method-specific gestation reference intervals for their population.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Medicine
Publisher:	SAGE Publications
ISSN:	0004-5632
Date of First Compliant Deposit:	26 January 2022
Date of Acceptance:	2 June 2021
Last Modified:	27 Jun 2024 11:20
URI:	https://orca.cardiff.ac.uk/id/eprint/146983

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