Khalid, AS,Marchocki, Z,Hayes, K,Lutomski, JE,Joyce, C,Stapleton, M,O'Mullane, J,O'Donoghue, K

2014

January

Annals Of Clinical Biochemistry

Establishing trimester-specific maternal thyroid function reference intervals

Published

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Thyroid hormones analytes pregnancy clinical studies immunoassay SUBCLINICAL HYPOTHYROIDISM FUNCTION TESTS TSH LEVELS PREGNANCY WOMEN GESTATION MISCARRIAGE RISK

51

277

283

Background Thyroid disorders are common in women of childbearing age and are associated with adverse pregnancy outcomes. Physiological changes in pregnancy and the lack of pregnancy-specific reference ranges make managing thyroid disorders in pregnancy challenging. Our aim was to establish trimester-specific thyroid function reference intervals throughout pregnancy, and to examine the prevalence of thyroid autoimmunity in otherwise euthyroid women.Method This was a prospective, cross-sectional study of thyroid function tests (TFTs) in pregnant women attending a large, tertiary referral maternity hospital. Patients with known thyroid disorders, autoimmune disease, recurrent miscarriage, hyperemesis gravidarum and pre-eclampsia were excluded. TFTs were analysed in the CUH biochemistry laboratory using Roche Modular E170 electrochemiluminescent immunoassay. Trimester-specific reference ranges (2.5th, 50th and 97.5th centiles) were calculated.Results Three-hundred-and-fifty-one women were included into the analysis. Median maternal age was 30. Thyroid-stimulating hormone concentrations showed slightly increasing median centile throughout gestation. Free thyroxine (T4) and T3 decreased throughout gestation. Table 1 demonstrates the calculated percentiles according to gestational weeks.Conclusion We established pregnancy-specific thyroid function reference intervals for our pregnant population, for use in clinical practice.

10.1177/0004563213496394