The Incidence of Gestational Hyperthyroidism and Postpartum Thyroiditis in Treated Patients with Graves' Disease

Kyōto Medical Center, Kioto, Kyōto, Japan
Thyroid (Impact Factor: 4.49). 09/2007; 17(8):767-72. DOI: 10.1089/thy.2007.0003
Source: PubMed


Graves' disease (GD) is one of the most common thyroid diseases that cause hyperthyroidism. Gestational transient thyrotoxicosis (GTT) is nonautoimmune hyperthyroidism that occurs in women with a normal pregnancy. Postpartum transient thyroiditis (PTT) is a destructive thyroiditis induced by autoimmune mechanism in the postpartum period. Hyperthyroidism due to GD usually tends to improve during the course of gestation and exacerbate after delivery. When the patient with treated GD presents with thyrotoxicosis in the early pregnancy or in the postpartum period, differential diagnosis of exacerbation of GD with GTT or PTT is important because the latter disorders are fundamentally transient. To evaluate the incidence of GTT and PTT in a GD population, we investigated the thyroid functions, thyrotropin receptor antibodies (TRAb), and human chorionic gonadotropin (hCG) during pregnancy and for 1 year after delivery for 39 pregnancies in 34 women with GD. The incidence of GTT was 26% (10/39) of pregnancies. The peak value of hCG in the GTT group ([23.7 +/- 14.5] x 10(4) IU/mL, n = 9) was significantly higher than that in the non-GTT group ([13.3 +/- 4.7] x 10(4) IU/mL, n = 19). The incidence of PTT was 44% (17/39) of deliveries. The free triiodothyronine (FT(3))/free thyroxine (FT(4)) ratio of the exacerbation group of GD (3.1 +/- 1.0, n = 10) at the time of thyrotoxicosis after delivery was significantly higher than that of the PTT group (2.5 +/- 0.4, n = 16). The peak TRAb value of the exacerbation group of GD (72.5 +/- 121.7 IU/L, n = 10) at the time of thyrotoxicosis after delivery was also significantly higher than that of the PTT group (1.4 +/- 0.8 IU/L, n = 16). In conclusion, the high peak value of hCG is valuable for suspecting GTT, and the high FT(3)/FT(4) ratio is valuable for suspecting recurrence in the patients with GD. In both situations, changes of TRAb were also valuable in differentiating the recurrence of GD from GTT or PTT.

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    • "However, this is variable, and in a study of 184 women in Singapore, the prevalence of GTT during the first trimester was much higher at 11% [4]. GTT is also more common in patients with a history of Graves' disease prior to pregnancy, in whom the prevalence can be as high as 25% [5]. The prevalence of overt thyrotoxicosis in pregnancy ranged from 0.2 to 0.7% in one large U.S. population sample [6]. "
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    ABSTRACT: Thyrotoxicosis presenting during pregnancy is a common clinical problem and can be challenging to differentiate between physiologic patterns of thyroid dysfunction during gestation and intrinsic hyperthyroidism. This review provides a summary of the differential diagnosis, clinical presentation, diagnostic options, potential adverse effects of maternal thyrotoxicosis to the fetus, and treatment recommendations for thyrotoxicosis arising in pregnancy.
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    Preview · Article · Dec 2007 · Thyroid
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