Thyroid Disorders During Pregnancy

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Physiology of thyroid gland in pregnancy

Normal pregnancy entails complex changes in thyroid physiology.4 Indeed, in pregnant women with hypothyroidism, exogenous thyroid hormone replacement requirements typically increase by 25% to 47% to maintain normal serum thyroid-stimulating hormone (TSH) concentrations.5, 6, 7 Several factors account for this. First, high estrogen states such as pregnancy increase hepatic thyroid-binding globulin (TBG) synthesis8, 9 and prolong TBG half-life because of estrogen-induced sialylation.10 In

Finding thyroid disorders in pregnancy: universal screening versus targeted high-risk case finding

Thyroid disorders are much more common in women than in men. In the last decade, there has been more attention paid to thyroid dysfunction during pregnancy and its effects on maternal and fetal well-being. As a result, there has been a debate regarding the use of universal screening versus targeted high-risk case finding for thyroid dysfunction during pregnancy. Different studies have shown that targeted high-risk screening failed to detect 28% to 36% of women with hypothyroidism.22, 23, 24 A

Hypothyroidism during pregnancy

Thyroid hormone deficiency is found in approximately 3% to 7% of women of child-bearing age,2 and an estimated 2% to 3% of women are hypothyroid during pregnancy.2, 3 In iodine-sufficient areas, the most common cause is Hashimoto thyroiditis. Other causes include prior radioactive iodine (RAI) and/or surgical ablation of Graves disease,30 surgical removal of the thyroid because of multinodular goiter or thyroid cancer, overtreatment of hyperthyroidism with thionamides, medications that alter

Euthyroidism with autoimmune thyroid disease

Approximately 12% of women of child-bearing age have detectable circulating thyroid autoantibodies.55 Several studies have shown an increased risk of pregnancy complications in euthyroid women with thyroid autoimmunity, including preterm delivery,56 spontaneous miscarriage,57 very preterm delivery (<34 weeks’ gestation),58 placental abruption,59 postpartum thyroiditis, and postpartum depression.60 Despite these findings, 2011 ATA guidelines state that there is insufficient evidence to recommend

Hyperthyroidism during pregnancy

Overt hyperthyroidism occurs in 0.4% to 1.7% of pregnant women, and Graves disease accounts for 85% to 90% of all cases.61 Other causes of hyperthyroidism in pregnancy include subacute thyroiditis, toxic multinodular goiter, toxic thyroid adenoma, and excessive levothyroxine intake.62 Maternal hyperthyroidism is defined as a low or suppressed serum TSH level in the presence of a high fT4 level based on trimester-specific reference ranges. As described earlier, serum TSH levels are normally

Postpartum thyroiditis

PPT is an autoimmune, destructive inflammation of the thyroid gland95 that typically occurs within 1 year postpartum. The classic presentation of PPT starts with transient hyperthyroidism in the first 6 months postpartum, followed by transient hypothyroidism, then a return to the euthyroid state by 1 year postpartum. Not all women with PPT progress through all the phases of this classic presentation. Lazarus and colleagues96 reported that, among a cohort of women diagnosed with PPT, 19.2%

Evaluation of thyroid nodules and thyroid cancer in pregnancy

Not uncommonly, thyroid nodules and thyroid cancer are diagnosed in women during or around the time of pregnancy, posing important diagnostic and therapeutic dilemmas when considering the best interests of both the mother and her developing child. Differentiated thyroid cancer (DTC) occurs approximately 3-fold more frequently in women than in men, with peak onset in the female reproductive years.109, 110 Many women come under closer medical evaluation around pregnancies than at any other time

Summary

  • The physiology of the thyroid gland changes during pregnancy as a result of the effects of increased TBG and hCG levels and enhanced iodine metabolism. It is important to use trimester-specific reference ranges for TFTs during pregnancy. TSH reference ranges decrease during pregnancy, especially in the first trimester. Total T4 and T3 levels increase because of increased TBG levels. The interpretation of levels of free thyroid hormone in pregnancy is more challenging.

  • Because of the lack of

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