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Journal of Thyroid Research
Volume 2012, Article ID 168764, 6 pages
http://dx.doi.org/10.1155/2012/168764
Clinical Study

Iodine Status Has No Impact on Thyroid Function in Early Healthy Pregnancy

1Department of Endocrinology, Diabetology and Reproductive Medicine, l’Archet Hospital, CHU de Nice, 151 route de Saint-Antoine, 06200 Nice, France
2Department of Biochemistry, CHU de Nice, 151 route de Saint-Antoine, 06200 Nice, France
3Department of Biostatistics, CHU de Nice, 151 route de Saint-Antoine, 06200 Nice, France

Received 1 May 2012; Accepted 19 October 2012

Academic Editor: Noriyuki Koibuchi

Copyright © 2012 F. Brucker-Davis et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Aim. To assess the impact of iodine status in early pregnancy on thyroid function. Methods. Women >18 years old seen at their first prenatal consult before 12 weeks of amenorrhea and without personal thyroid history were proposed thyroid screening and were eligible if they had strictly normal thyroid tests (fT4 > 10th percentile, TSH < 2.5 mUI/L, negative anti-TPO antibodies). Evaluation included thyroid ultrasound, extensive thyroid tests, and ioduria (UIE). Results. 110 women (27.5 y, 8 weeks of amenorrhea, smoking status: 28% current smokers) were enrolled. Results are expressed as medians. UIE was 116 μg/L. 66.3% of women had iodine deficiency (ID) defined as UIE < 150. FT4 was 14.35 pmol/L; TSH 1.18 mUI/L; fT3 5 pmol/L; thyroglobulin 17.4 ng/mL; rT3 0.27 ng/mL; thyroid volume: 9.4 ml. UIE did not correlate with any thyroid tests, but correlated negatively with thyroid volume. UIE and all thyroid tests, except fT3, correlated strongly with βhCG. Smoking correlated with higher thyroid volume and thyroglobulin and with lower rT3. Conclusions. In pregnant women selected for normal thyroid function, mild ID is present in 66% during the 1st trimester. The absence of correlation between UIE and thyroid tests at that stage contrasts with the impact of βhCG and, to a lesser degree, maternal smoking.