Thyroid reference ranges in pregnancy utilizing an Abbott Alinity platform in a multi-ethnic population in the UK

BackgroundMaternal thyroid function significantly affects fetal development. However, thyroid hormone concentrations change dynamically throughout pregnancy rendering non-pregnancy reference ranges inaccurate. We aimed to establish the trimester-, population-, and assay-specific reference ranges for thyroid hormones in pregnancy using the recently introduced Abbott Alinity thyroid function test, according to American Thyroid Association 2017 Guidelines for the Diagnosis and Management of Thyroid Disease During Pregnancy and the Postpartum.MethodsThis study of 663, iodine-replete and thyroid peroxidase (TPO)-antibody negative female determined trimester-specific reference ranges for thyroid stimulating hormone (TSH), free thyroxine (fT4), and free tri-iodothyronine (fT3) using Abbott Alinity assays in accordance with ATA guidelines. Study participants were drawn from a multi-ethnic population with 49% non-white participants.ResultsFirst trimester reference ranges were TSH 0.06-2.73 mIU/l, fT4 9.9-15.3 pmol/l, and fT3 3.4-5.6 pmol/l. Second trimester reference ranges were TSH 0.02-2.47 mIU/l, fT4 8.5-14.4 pmol/l, and fT3 3.3-5.5 pmol/l. In the third trimester, TSH ranges were 0.41-2.80 mIU/l, fT4 7.6-12.3 pmol/l, and fT3 3.1-5.0 pmol/l. There were no significant differences in any trimester-specific analyte reference ranges when white and non-white populations were compared.ConclusionsThese reference ranges support the clinical care of female from diverse backgrounds with thyroid dysfunction in pregnancy using the thyroid function tests available on the Abbott Alinity platform.Study registrationISRCTN17018939.