Search Results
Institut National de la Recherche Médicale, UMR U895, Université Nice-Sophia Antipolis, Nice, France
Search for other papers by Françoise Brucker-Davis in
Google Scholar
PubMed
Search for other papers by Patricia Panaïa-Ferrari in
Google Scholar
PubMed
Search for other papers by Jocelyn Gal in
Google Scholar
PubMed
Institut National de la Recherche Médicale, UMR U895, Université Nice-Sophia Antipolis, Nice, France
Search for other papers by Patrick Fénichel in
Google Scholar
PubMed
Search for other papers by Sylvie Hiéronimus in
Google Scholar
PubMed
Objectives: The aim of the study was to determine the evolution of thyroid tests throughout pregnancy and postpartum in healthy women with and without iodine supplementation. Methods: This was a prospective, randomized, interventional study of iodine supplementation (150 μg/day) from the first trimester until 3 months postpartum versus controls. 111 pregnant women with normal initial thyroid tests were enrolled, undergoing comprehensive thyroid assessment at each trimester. We present results of longitudinal and cross-sectional analyses. Results: Initial ioduria suggested mild iodine deficiency in both groups, while third-trimester ioduria rose to levels of iodine sufficiency in the iodine-supplemented group. In the longitudinal study, free T4 (FT4) levels decreased in the second and third trimesters compared to the first trimester in both groups, with no change in TSH, and rose postpartum, though lower than the first trimester. FT3 levels and the total T4 (TT4)/thyroxine-binding globulin (TBG) ratio followed the same evolution as FT4. TT4 levels rose due to TBG increase. Thyroglobulin (Tg) of iodine group remained stable, contrasting with the rise in the control group. In the cross-sectional study, there was no difference between the two groups in thyroid tests at any time-point, except for lower Tg in the second trimester and postpartum visits in the iodine group. Conclusions: In healthy, mildly iodine-deficient pregnant women, a ‘drop' of FT4 and TT4/TBG without TSH increase occurs between the first and second trimesters, and is not prevented by iodine supplementation, suggesting physiology. Therefore, FT4 is valuable to assess thyroid function in pregnancy in clinical practice with appropriate trimester-specific reference range. It brings up reflection on threshold for diagnosis and treatment of hypothyroxinemia.
Search for other papers by Sylvie Hiéronimus in
Google Scholar
PubMed
Search for other papers by Patricia Ferrari in
Google Scholar
PubMed
Search for other papers by Jocelyn Gal in
Google Scholar
PubMed
Search for other papers by Frédéric Berthier in
Google Scholar
PubMed
Search for other papers by Stéphane Azoulay in
Google Scholar
PubMed
Search for other papers by André Bongain in
Google Scholar
PubMed
Institut National de la Recherche Médicale, UMR U895, University Nice-Sophia-Antipolis, Nice, France
Search for other papers by Patrick Fénichel in
Google Scholar
PubMed
Institut National de la Recherche Médicale, UMR U895, University Nice-Sophia-Antipolis, Nice, France
Search for other papers by Françoise Brucker-Davis in
Google Scholar
PubMed
Objective: To assess the impact on cord blood (CB) thyroglobulin (Tg) of early iodine supplementation during pregnancy. Methods: A total of 111 healthy pregnant women with normal thyroid function were included in a prospective randomized study and divided into two groups with (150 µg/day) or without iodine supplementation started during the first trimester. Maternal smoking was assessed qualitatively by self-reported statements and quantitatively by cotininuria. Exhaustive thyroid tests were performed at delivery in the mother and in CB. Results: Third-trimester ioduria documented compliance with iodine supplementation (160 vs. 76 µg/l in controls). CB Tg was not different between the iodine and control groups (median 77 vs. 79.5 ng/ml, respectively) and did not correlate with maternal ioduria. CB Tg was higher in newborns from smoking mothers (114 vs. 64.7 ng/ml) and correlated with self-reported smoking status more than with maternal cotininuria. Nonsmokers had no difference in CB Tg whether they took iodine supplementation or not, as opposed to smokers, who tended to benefit from supplementation. Conclusions: Iodine supplementation does not significantly impact CB Tg in healthy nonsmoker pregnant women selected for normal thyroid function, as opposed to maternal smoking. CB Tg appears to be a marker of in utero tobacco exposure. In areas of mild iodine deficiency, iodine supplementation could especially benefit the fetuses of smokers.