The Relationship of Preconception Thyrotropin Levels to Requirements for Increasing the Levothyroxine Dose During Pregnancy in Women with Primary Hypothyroidism

Abalovich, Marcos; Alcaraz, Graciela; Kleiman-Rubinsztein, Jessica; Pavlove, María Magdalena; Cornelio, Cecilia; Levalle, Oscar; Gutiérrez, Sílvia

doi:10.1089/thy.2009.0457

Cited by 76 publications

(42 citation statements)

References 21 publications

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“…Others advocate that preconception TSH levels be lower than 1.2 mIU/L. In a study favoring the latter, only 17% of women with TSH values under this cutoff had to increase LT 4 dose later during pregnancy (58). Separate, however, from preconception TSH values, it is increasingly apparent that other factors can also influence the rapidity and extent of LT 4 augmentation necessary to maintain a euthyroid state during pregnancy.…”

Section: Question 9: Should Oh Be Treated In Pregnancy?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

2,054

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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Section: Question 9: Should Oh Be Treated In Pregnancy?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

2,054

2,716

View full text Add to dashboard Cite

show abstract

“…As shown in Table 1, these criteria unfortunately varied substantially among the available evidence. In this regard, it is worth noting that only Abalovich et al (21) referred to the same criteria used in our study. Interestingly, these authors reported a 32% rate of adjustment, markedly lower than the 84% observed in our series.…”

Section: Clinical Study a Busnelli And Others Levothyroxine Adjustmenmentioning

confidence: 92%

“…Both Abalovich et al (21) and Kothari & Girling (24) observed that, before pregnancy, the mean TSH value was lower in women who did not need additional L-T 4 during pregnancy than in those who needed an increase. Abalovich et al (21) also observed that only 17% of women with a preconception TSH lower than 1.2 mIU/l had to increase the L-T 4 dose during pregnancy (21). Inconsistency with our findings may be explained by a type 2 error.…”

Section: Clinical Study a Busnelli And Others Levothyroxine Adjustmenmentioning

confidence: 96%

Levothyroxine dose adjustment in hypothyroid women achieving pregnancy through IVF

Busnelli

Vannucchi

Paffoni

et al. 2015

European Journal of Endocrinology

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Objective: About one out of two women with primary hypothyroidism has to increase the dosage of exogenous levothyroxine (L-T 4 ) during pregnancy. Considering the detrimental impact of IVF on thyroid function, it has been claimed but not demonstrated that L-T 4 dose adjustment may be more significant in hypothyroid women who become pregnant after IVF. Design: Retrospective cohort study. Methods: Hypothyroid-treated women who achieved a live birth through IVF were reviewed. Women could be included if thyroid function was well compensated with L-T 4 before the IVF cycle (i.e., serum TSH !2.5 mIU/l and serum free T 4 within the normal range). Serum TSH and dose adjustment were evaluated at five time points during pregnancy. The trimester ranges for serum TSH considered as reference to adjust L-T 4 therapy were 0.1-2.5 mIU/l for the first trimester, 0.2-3.0 mIU/l for the second trimester, and 0.3-3.0 mIU/l for the third trimester. Results: Thirty-eight women were selected. During the whole pregnancy 32 women (84%; 95% CI: 72-96%) required an increase in the dose of L-T 4 . In most cases (nZ28), this occured within the first 5-7 weeks of gestation (74%, 95% CI: 58-85%). At 5-7 weeks of gestation, the median (interquartile range) increase of L-T 4 dose for the whole cohort was 26% (0-50%). At 30-32 weeks, it was 33% (14-68%). In order to identify predictive factors of dose adjustment, we compared women who did (nZ28) and did not (nZ10) adjust L-T 4 dosage at 5-7 weeks' gestation. Significant differences emerged for thyroid autoimmunity prevalence and for the distribution of hypothyroidism aetiology. Conclusions: The vast majority of hypothyroid-treated women who achieve pregnancy through IVF need an increase in the L-T 4 dose during gestation. This requirement tends to occur very early during gestation.

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“…Meanwhile it is reasonable practice to maintain TSH values in women planning pregnancy below 2.5 mU/l, especially in those with positive TPOAb; newly diagnosed patients should be treated in order to normalize maternal serum TSH values within the trimester-specific pregnancy reference range [89]. …”

Section: Effects Of Treatment Of Sch and Ih With Levothyroxinementioning

confidence: 99%

2014 European Thyroid Association Guidelines for the Management of Subclinical Hypothyroidism in Pregnancy and in Children

Lazarus¹,

Brown²,

Daumerie³

et al. 2014

Eur Thyroid J

601

457

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This guideline has been produced as the official statement of the European Thyroid Association guideline committee. Subclinical hypothyroidism (SCH) in pregnancy is defined as a thyroid-stimulating hormone (TSH) level above the pregnancy-related reference range with a normal serum thyroxine concentration. Isolated hypothyroxinaemia (defined as a thyroxine level below the 2.5th centile of the pregnancy-related reference range with a normal TSH level) is also recognized in pregnancy. In the majority of SCH the cause is autoimmune thyroiditis but may also be due to iodine deficiency. The cause of isolated hypothyroxinaemia is usually not apparent, but iodine deficiency may be a factor. SCH and isolated hypothyroxinaemia are both associated with adverse obstetric outcomes. Levothyroxine therapy may ameliorate some of these with SCH but not in isolated hypothyroxinaemia. SCH and isolated hypothyroxinaemia are both associated with neuro-intellectual impairment of the child, but there is no evidence that maternal levothyroxine therapy improves this outcome. Targeted antenatal screening for thyroid function will miss a substantial percentage of women with thyroid dysfunction. In children SCH (serum TSH concentration >5.5-10 mU/l) normalizes in >70% and persists in the majority of the remaining patients over the subsequent 5 years, but rarely worsens. There is a lack of studies examining the impact of SCH on the neuropsychological development of children under the age of 3 years. In older children, the evidence for an association between SCH and impaired neuropsychological development is inconsistent. Good quality studies examining the effect of treatment of SCH in children are lacking.

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The Relationship of Preconception Thyrotropin Levels to Requirements for Increasing the Levothyroxine Dose During Pregnancy in Women with Primary Hypothyroidism

Abstract: We suggest that in women with hypothyroidism who are planning to become pregnant, serum TSH levels should be in the normal range but should not be greater than about 1.2 mIU/mL.

Cited by 76 publications

References 21 publications

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

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

Levothyroxine dose adjustment in hypothyroid women achieving pregnancy through IVF

2014 European Thyroid Association Guidelines for the Management of Subclinical Hypothyroidism in Pregnancy and in Children

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