First- and second-trimester thyroid hormone reference data in pregnant women: a FaSTER (First- and Second-Trimester Evaluation of Risk for aneuploidy) Research Consortium study

Lambert-Messerlian, Geralyn; McClain, Monica R.; Haddow, James E.; Palomaki, Glenn E.; Canick, Jacob A.; Cleary-Goldman, Jane; Malone, Fergal D.; Porter, T. Flint; Nyberg, David A.; Bernstein, Peter S.; D’Alton, Mary E.

doi:10.1016/j.ajog.2007.12.003

Cited by 104 publications

(52 citation statements)

References 17 publications

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“…Unfortunately, this source of biologic variability cannot be accounted for when providing interpretations for clinical purposes, as there is no practical way to establish baseline reference ranges for each individual within a given population. 1 In 2008, we observed a relationship between low free T4 (FT4) concentration and higher maternal weight and body mass index (BMI) during early pregnancy (15-20 gestational weeks) (2,3). In that study, BMI averaged 2.9 kg/m 2 higher (17 lb) in association with FT4 concentrations below the 2.5th centile.…”

Section: Introductionmentioning

confidence: 81%

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Impact of Adjusting for the Reciprocal Relationship Between Maternal Weight and Free Thyroxine During Early Pregnancy

Haddow

Craig

Palomaki

et al. 2013

Thyroid

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for the First and Second Trimester Risk of Aneuploidy (FaSTER) Research ConsortiumBackground: Among euthyroid pregnant women in a large clinical trial, free thyroxine (FT4) measurements below the 2.5th centile were associated with a 17 lb higher weight (2.9 kg/m 2 ) than in the overall study population. We explore this relationship further. Methods: Among 9351 women with second trimester thyrotropin (TSH) measurements between 1st and 98th centiles, we examine: (i) the weight/FT4 relationship; (ii) percentages of women in three weight categories at each FT4 decile; (iii) FT4 concentrations in three weight categories at each TSH decile; and (iv) impact of adjusting FT4 for weight-in the reference group and in 190 additional women with elevated TSH measurements. Results: FT4 values decrease steadily as weight increases ( p < 0.0001 by ANOVA) among women in the reference group (TSH 0.05-3.8 IU/L). TSH follows no consistent pattern with weight. When stratified into weight tertiles, 48% of women at the lowest FT4 decile are heavy; the percentage decreases steadily to 22% at the highest FT4 decile. Median FT4 is lowest in heaviest women regardless of the TSH level. In the reference group, weight adjustment reduces overall variance by 2.9%. Fewer FT4 measurements are at either extreme (below the 5th FT4 centile: 4.8% before adjustment, 4.7% after adjustment; above the 95th FT4 centile: 5.0% and 4.7%, respectively). Adjustment places more light weight women and fewer heavy women below the 5th FT4 centile; the converse above the 95th centile. Between TSH 3.8 and 5 IU/L, the FT4 percentage below the 5th FT4 centile is not elevated (3.8% before adjustment, 3.1% after adjustment). Percentage of FT4 values above the 95th centile, however, is lower (1.5% before adjustment, 0.8% after adjustment). Above TSH 5 IU/L, 25% of women have FT4 values below the 5th FT4 centile; weight adjustment raises this to 30%; no FT4 values remain above the 95th FT4 centile. Conclusions: During early pregnancy, TSH values are not associated with weight, unlike nonpregnant adults. Lower average FT4 values among heavy women at all TSH deciles partially explain interindividual differences in FT4 reference ranges. The continuous reciprocal relationship between weight and FT4 explains lower FT4 with higher weight. Weight adjustment refines FT4 interpretation.

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Section: Introductionmentioning

confidence: 81%

“…Women were participants in the multicenter FaSTER trial, as previously described (2,3). Enrollment was limited to women with singleton pregnancies.…”

Section: Methodsmentioning

confidence: 99%

Impact of Adjusting for the Reciprocal Relationship Between Maternal Weight and Free Thyroxine During Early Pregnancy

Haddow

Craig

Palomaki

et al. 2013

Thyroid

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“…Furthermore, prospective studies have demonstrated that untreated subclinical hyperthyroidism is not associated with maternal or fetal adverse outcomes. Perhaps this is secondary to the fact that (85,86,124,125). Taking into account the large sample of subjects included in these studies, the data obtained should be rigourously validated before being used in clinical practice.…”

Section: European Journal Of Endocrinologymentioning

confidence: 99%

CONTROVERSIES IN ENDOCRINOLOGY: On the need for universal thyroid screening in pregnant women

Vila

Velasco

González

et al. 2014

European Journal of Endocrinology

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There is a well-known controversy among scientific societies regarding the recommendation to screen for thyroid dysfunction (TD) during pregnancy. Although several studies have shown an association between maternal subclinical hypothyroidism and/or hypothyroxinemia with obstetric problems and/or neurocognitive impairment in the offspring, there is only limited evidence on the possible positive effects of thyroxine (T 4 ) treatment in such cases. Despite the scarcity of this evidence, there is a widespread agreement among clinicians on the need for treatment of clinical hypothyroidism during pregnancy and the risks that could arise due to therapeutic abstention. As maternal TD is a quite prevalent condition, easily diagnosed and for which an effective and safe treatment is available, some scientific societies have proposed to assess thyroid function during the first trimester of pregnancy and ideally before week 10 of gestational age. Given the physiologic changes of thyroid function during pregnancy, hormone assessment should be performed using trimester-specific reference values ideally based on locally generated data as geographic variations have been detected. Screening of TD should be based on an initial determination of TSH performed early during the first trimester and only if abnormal should it be followed by either a free or total T 4 measurement. Furthermore, adequate iodine supplementation during pregnancy is critical and if feasible it should be initiated before the woman attempts to conceive.

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“…Placental production of human chorionic gonadotrophin (hCG) and a rise in oestrogen production that increases binding proteins, namely thyroxinebinding globulin affect free TH levels. TSH dips according to most but not all studies within the first trimester, whereas free TH concentrations decrease, albeit very slightly, mainly during the latter part of pregnancy (10,11,14,15,16,17,18,19). These observed alterations are not only due to pathophysiological changes but are, at least in part, due to methodological issues.…”

Section: Changes Of Tsh Ths and Iodine During Pregnancymentioning

confidence: 91%

“…The depth, rate and timing of the first-trimester dip in TSH scatter widely between studies and with marked interindividual variability within studies (10,14,15,17,18,19). Methodological differences amongst TSH assay platforms may explain some of the variation.…”

Section: Changes Of Tsh Ths and Iodine During Pregnancymentioning

confidence: 99%

Management of subclinical hypothyroidism in pregnancy: are we too simplistic?

Brabant

Peeters²,

Chan

et al. 2015

European Journal of Endocrinology

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Guideline advice of many societies on the management of subclinical hypothyroidism in pregnancy suggests treatment when TSH serum levels exceed 2.5 mU/l. Justification of this procedure is based on limited experience, mainly from studies carried out in patients with positive thyroid-specific antibodies and higher TSH levels that classically define the condition in the nonpregnant state. Taking into account a lack of clear understanding of the regulation of thyroid hormone transport through the utero-placental unit and in the absence of foetal markers to monitor the adequacy of thyroxine treatment, this review attempts to discuss currently available data and suggests a more cautious approach.

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First- and second-trimester thyroid hormone reference data in pregnant women: a FaSTER (First- and Second-Trimester Evaluation of Risk for aneuploidy) Research Consortium study

Cited by 104 publications

References 17 publications

Impact of Adjusting for the Reciprocal Relationship Between Maternal Weight and Free Thyroxine During Early Pregnancy

Impact of Adjusting for the Reciprocal Relationship Between Maternal Weight and Free Thyroxine During Early Pregnancy

CONTROVERSIES IN ENDOCRINOLOGY: On the need for universal thyroid screening in pregnant women

Management of subclinical hypothyroidism in pregnancy: are we too simplistic?

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