Thyroid for thyroid function test reference intervals during pregnancy using the Vitros 5600.

E Haworth, C Chang, T Yen, A Chiriano, S Matthews

Research output: Contribution to journalMeeting Abstractpeer-review

Abstract

Introduction

Harmonization of reference intervals (RI) for thyroid function tests (TFT) is restricted by assay variation, but the derivation of ‘method-specific’ TFT RI has been recommended by professional working parties. This study aims to develop evidence-based, Ortho Clinical Diagnostics (OCD) RI for TSH, fT4 and fT3 in pregnancy, since our laboratory is one of few to report TFT results for this method group in the RCPA QAP Endocrine Program.

Methods

We compared OCD (Vitros 5600) TSH, fT4 and fT3 in pregnant patients with results from Abbott Architect Systems, a frequently used method, to define method-specific variation. The Abbott Architect correlation data and published RI review ‘anchored’ the patient (n=4405) derived, trimester specific RI for OCD TSH, fT4 and fT3 assays.

Results

OCD and Abbott Architect TSH results (0–8 mIU/L) correlated well (r2=0.993), with insignificant bias (y=0.956x – 0.079). Patient data and literature analysis supported 1st trimester (0.09–2.82 mIU/L), 2nd trimester (0.20–2.79 mIU/L) and 3rd trimester (0.31–2.90 mIU/L) RI for OCD TSH.

OCD and Abbott Architect fT4 results (6–20 pmol/L) correlated (r2=0.929), but OCD fT4 values <12 pmol/L showed negative bias (y=0.766x + 3.702). Patient data and literature analysis supported 1st trimester (10.0–25.0 pmol/L), 2nd trimester (9.0–19.0pmol/L) and 3rd trimester (8.0–19.6 pmol/L) RI for OCD fT4.

There was poor correlation (r2=0.6141) for OCD and Abbott Architect fT3 values between 2–6 pmol/L. Patient data and literature analysis supported 1st trimester (3.5–6.2 pmol/L), 2nd trimester (3.4–5.8pmol/L) and 3rd trimester (3.3–5.6 pmol/L) RI for OCD fT3.

Conclusion

Abbott Architect correlation data and published TFT RIs ‘anchored’ the review of patient derived, trimester specific RI for OCD TSH, fT4 and fT3. A review of patient data “flagging rates” and clinical consultation confirmed the validity of the derived OCD TSH, fT4 and fT3 RI, prior to implementation.

Original languageEnglish
Article numberP71
Number of pages1
JournalClinical Biochemist Reviews
Volume36
Issue numberSuppl
Publication statusPublished - 2015
Externally publishedYes
EventAustralasian Association of Clinical Biochemists 53rd Annual Scientific Conference - ANZ Stadium, Sydney Olympic Park, Sydney, Australia
Duration: 15 Sep 201517 Sep 2015
Conference number: 53rd

Keywords

  • thyroid function test
  • TFT
  • Pregnancy
  • gestational
  • reference intervals

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