Ethnic differences in TSH but not in free T4 concentrations or TPO antibodies during pregnancy

Benhadi, N.; Wiersinga, Wilmar M.; Reitsma, Johannes B.; Vrijkotte, Tanja G. M.; Wal, Marcel F. van der; Bonsel, Gouke J.

doi:10.1111/j.1365-2265.2007.02803.x

Cited by 77 publications

(51 citation statements)

References 20 publications

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“…The latter possibility would indicate real differences in the setpoint of the HPT axis between our subjects. Indeed ethnic differences in ambient TSH values but not in FT 4 values suggest an effect of race (17,18), and slightly lower TSH values have been observed in carriers of the Asp727Glu polymorphism in the TSH receptor gene occurring in about 20% of a Caucasian population (19). The low prevalence of this TSH receptor polymorphism does not favour possibility iii) in our (mostly Caucasian) subjects.…”

Section: Discussionmentioning

confidence: 68%

Pilot study on the assessment of the setpoint of the hypothalamus–pituitary–thyroid axis in healthy volunteers

Benhadi

Fliers

Visser

et al. 2010

European Journal of Endocrinology

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Objective: To determine the log-linear relationship between TSH and free thyroxine in healthy subjects, and the variation in baseline TSH/free thyroxine (FT 4 ) combination in each individual. Subjects and methods: Twenty-one healthy volunteers (nine males and 12 females; mean age 60 years, range 51-74) were randomized to receive at 2300 h with 2-week intervals a single dose of placebo, 125 mg T 4 and 250 mg T 4 (arm 1, nZ10), or placebo, 25 mg triiodothyronine (T 3 ) and 50 mg T 3 (arm 2, nZ11). Blood samples were taken in the morning (0800-1100 h) before and following the administration of the drug for the assessment of TSH, FT 4 and T 3 . Results: Intra-and inter-individual variation and the individuality index of the four baseline serum samples were respectively 21.6%, 41.9% and 0.52 for TSH; 9.9%, 16.5% and 0.60 for FT 4 ; and 9.3%, 16.0% and 0.58 for T 3 . Substantial differences existed in the location of individual working points within the reference range. T 4 administration increased FT 4 (but not T 3 ) and decreased TSH, resulting in a log-linear relationship (log TSHZ1.50-0.059!FT 4 , P!0.05) for the whole group. T 3 administration increased T 3 and decreased TSH (but not FT 4 ), resulting in a log-linear relationship (log TSHZ0.790-0.245!T 3 , P!0.001) for the whole group. Log-linear relationships were not always significant when assessed for each subject separately. Conclusion: Individuality indices of TSH, FT 4 and T 3 are all %0.6, thereby limiting the usefulness of the population-based reference values. Accurate assessment of individual setpoints of the HPT axis was not possible with the applied single doses of T 4 or T 3 , and will require either prolonged administration or higher single doses of thyroid hormone.

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Section: Discussionmentioning

confidence: 68%

Pilot study on the assessment of the setpoint of the hypothalamus–pituitary–thyroid axis in healthy volunteers

Benhadi

Fliers

Visser

et al. 2010

European Journal of Endocrinology

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“…Black and Asian women have TSH values that are on average 0.4 mIU/L lower than in white women; these differences persist during pregnancy (21,22). Pregnant women of Moroccan, Turkish, or Surinamese descent residing in The Netherlands, have TSH values 0.2-0.3 mIU/L lower than Dutch women throughout pregnancy (23). TSH ranges vary slightly depending on differences between methods of analysis (24).…”

mentioning

confidence: 99%

2017 Guidelines of the American Thyroid Association for the Diagnosis and Management of Thyroid Disease During Pregnancy and the Postpartum

Alexander

Pearce

Brent

et al. 2017

Thyroid

1,997

2,716

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INTRODUCTION Pregnancy has a profound impact on the thyroid gland and thyroid function. The gland increases 10% in size during pregnancy in iodine-replete countries and by 20%-40% in areas of iodine deficiency. Production of thyroxine (T 4 ) and triiodothyronine (T 3 ) increases by 50%, along with a 50% increase in the daily iodine requirement. These physiological changes may result in hypothyroidism in the later stages of pregnancy in iodine-deficient women who were euthyroid in the first trimester. The range of thyrotropin (TSH), under the impact of placental human chorionic gonadotropin (hCG), is decreased throughout pregnancy with the lower normal TSH level in the first trimester being poorly defined and an upper limit of 2.5 mIU/L. Ten percent to 20% of all pregnant women in the first trimester of pregnancy are thyroid peroxidase (TPO) or thyroglobulin (Tg) antibody positive and euthyroid. Sixteen percent of the women who are euthyroid and positive for TPO or Tg antibody in the first trimester will develop a TSH that exceeds 4.0 mIU/L by the third trimester, and 33%-50% of women who are positive for TPO or Tg antibody in the first trimester will develop postpartum thyroiditis. In essence, pregnancy is a stress test for the thyroid, resulting in hypothyroidism in women with limited thyroidal reserve or iodine deficiency, and postpartum thyroiditis in women with underlying Hashimoto's disease who were euthyroid prior to conception.Knowledge regarding the interaction between the thyroid and pregnancy/the postpartum period is advancing at a rapid pace. Only recently has a TSH of 2.5 mIU/L been accepted as the upper limit of normal for TSH in the first trimester. This has important implications in regards to interpretation of the literature as well as a critical impact for the clinical diagnosis of hypothyroidism. Although it is well accepted that overt hypothyroidism and overt hyperthyroidism have a deleterious impact on pregnancy, studies are now focusing on the potential impact of subclinical hypothyroidism and subclinical hyperthyroidism on maternal and fetal health, the association between miscarriage and preterm delivery in euthyroid women positive for TPO and/or Tg antibody, and the prevalence and long-term impact of postpartum thyroiditis. Recently completed prospective randomized studies have begun to produce critically needed data on the impact of treating thyroid disease on the mother, fetus, and the future intellect of the unborn child.It is in this context that the American Thyroid Association (ATA) charged a task force with developing clinical guidelines on the diagnosis and treatment of thyroid disease during pregnancy and the postpartum. The task force consisted of international experts in the field of thyroid disease and pregnancy, and included representatives from the ATA, Asia and Oceania Thyroid Association, Latin American Thyroid Society, American College of Obstetricians and Gynecologists, and the Midwives Alliance of North America. Inclusion of thyroidologists, obstetricians, and midwives ...

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“…13,20 Black and Asian women have TSH values that are on average 0.4 mIU/ L lower than in white women; these differences persist during pregnancy. 20,21,22 Pregnant women of Moroccan, Turkish, or Surinamese descent residing in the Netherlands, have TSH values 0.2-0.3 mIU/L lower than Dutch women throughout pregnancy. 21 Kumar and associates found that mean T 4 levels began to rise from 16.45 pmol/L in the first trimester to 16.58 pmol/L in the second trimester and then decreased in the third trimester to 15.99 pmol/L, they also reported that mean TSH level also rise progressively through the three trimesters of pregnancy from 1.20 mlU/ L in the first trimester to 2.12 mIU/L in the second trimester and further to 3.30 mIU/L in the third trimester of pregnancy, which was not consistent with this study findings.…”

Section: Discussionmentioning

confidence: 99%

Screening of Thyroid Function in the First Half of Pregnancy

Tania¹,

Islam

2016

Bangladesh J Obstet Gynaecol

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Objective: The study was conducted to find out any alterations in thyroid function status in first half of pregnancy (up to 20 weeks), with ultimate aim of deciding the usefulness of routine screening of thyroid function in pregnancy.Material and methods: A cross-sectional study was conducted in the department of Obstetrics & Gynaecology, Dhaka Medical College and Hospital, Dhaka, Bangladesh, over a period of one year from July 2011 to June 2012 on pregnant women in their 1st half of pregnancy to screen for the thyroid function. Based on predefined eligibility criteria, a total of 230 pregnant women were purposively included in the study. Thyroid function status was assessed by measuring serum levels of TSH, free thyroxine (FT4), and free tri-iodothyronine (FT3). Women with thyroid disorders were excluded.Results: The mean age of the patients being 24 years. Over 90% of the women were housewife and majority (88.7%) was educated. Over one-quarter of women was overweight with mean body mass index being 22.1 ± 4.4 kg/m2. The women were predominantly multigravida with 56% in 1st trimester 44% in the 1st half of 2nd trimester of pregnancy (13-20 weeks). Based on trimesters specific range of serum TSH in the 1st and 1st half of 2nd trimester (13-20 weeks) of pregnancy,13% of the patients were hypothyroid and 3% were hyperthyroid thus yielding a total of 37(16%) pregnant women with abnormal thyroid function status.Conclusion: The study concluded that one in every six women may have thyroid disorder in the first half of pregnancy and subclinical hypothyroidism is four times more common than the subclinical hyperthyroidism.Bangladesh J Obstet Gynaecol, 2014; Vol. 29(1) : 26-31

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Ethnic differences in TSH but not in free T4 concentrations or TPO antibodies during pregnancy

Abstract: The increase in TSH and decrease in free T4 values during pregnancy correspond to previous reported studies. Pregnant Dutch women had consistently higher TSH values than the ethnic group, but corresponding free T4 levels and TPO-Ab did not differ between these ethnic groups.

Cited by 77 publications

References 20 publications

Pilot study on the assessment of the setpoint of the hypothalamus–pituitary–thyroid axis in healthy volunteers

Pilot study on the assessment of the setpoint of the hypothalamus–pituitary–thyroid axis in healthy volunteers

2017 Guidelines of the American Thyroid Association for the Diagnosis and Management of Thyroid Disease During Pregnancy and the Postpartum

Screening of Thyroid Function in the First Half of Pregnancy

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