Ethnic Differences in Maternal Thyroid Parameters during Pregnancy: The Generation R Study

Tim Korevaar, Marco Medici, Yolanda de Rijke, Willy Visser, Sabine Schrama, Vincent Jaddoe, Bert Hofman, HA Ross, Edward Visser, H (Herbert) Hooijkaas, Eric Steegers, Henning Tiemeier, JJ Bongers - Schokking, Theo Visser, Robin Peeters

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Abstract

Context: Abnormal maternal thyroid function during pregnancy is associated with various complications. International guidelines advocate the use of population-based trimester-specific reference ranges for thyroid function tests. When unavailable, an upper TSH limit of 2.5 for the first trimester and 3.0 mU/L for the second and third trimesters is recommended. Although interindividual differences in thyroid function tests can partially be explained by ethnicity, data on the influence of ethnicity on TSH and free T-4 reference ranges during pregnancy are sparse. Design: Serum TSH, free T-4, T-4, and TPO-antibody levels were determined during early pregnancy in 3944 women from the Generation R study, Rotterdam, The Netherlands. Results: The study population consisted of 2765 Dutch, 308 Moroccan, 421 Turkish, and 450 Surinamese women. Mean TSH levels were higher in Dutch and Turkish women than in Moroccan or Surinamese women (1.50-1.48 vs 1.29-1.33 mU/L; P<.01). Although no differences in free T-4 were seen, T-4 was lowest in Dutch women (142 vs 150-156 nmol/L; P<.01). Turkish women had the highest frequency of TPO-antibody positivity (9.3% vs 5.0-5.8%; P<.05) and of elevated TSH levels in the second trimester (11.0% vs Conclusions: We show ethnic differences in serum TSH, T-4, and TPO-antibody positivity and found significant diagnostic discrepancies depending on whether population or ethnicity-specific reference ranges were used to diagnose thyroid disease. (J Clin Endocrinol Metab 98: 3678-3686, 2013)
Original languageUndefined/Unknown
Pages (from-to)3678-3686
Number of pages9
JournalJournal of Clinical Endocrinology and Metabolism
Volume98
Issue number9
DOIs
Publication statusPublished - 2013

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