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Women with Graves’ disease may have postpartum thyroiditis or postpartum exacerbation of Graves’ disease
The background of the study. Women with hyperthyroidism due to Graves’ disease may have hyperthyroidism after pregnancy caused either by thyroid inflammation (postpartum thyroiditis) or a postpartum exacerbation of Graves’ hyperthyroidism. This study was done to determine the frequency and characteristics of these two types of hyperthyroidism.
How the study was done. The study subjects were 34 women with Graves’ hyperthyroidism who were followed during and for one year after 39 pregnancies. The women were in remission before 16 pregnancies, and were treated with an antithyroid drug during 23 pregnancies. Serum thyrotropin (TSH), free thyroxine (T4), and TSH receptor-stimulating antibodies (TSHR-SAb) (which cause Graves’ hyperthyroidism) were measured during pregnancy, one month after delivery, and at one- to three-month intervals for one year after delivery.
Postpartum thyroiditis was defined as transient postpartum hyperthyroidism followed by transient hypothyroidism, lasting no more than three months, and postpartum exacerbation of Graves’ disease as hyperthyroidism lasting for at least four months.
The results of the study. Seventeen pregnancies (44 percent) were followed by postpartum thyroiditis. Eleven pregnancies (28 percent) were followed by a postpartum exacerbation of Graves’ hyperthyroidism (Table). The mean time to onset of hyperthyroidism was 4.5 months in the postpartum-thyroiditis group, as compared with 5.2 months in the postpartum-exacerbation group. The peak serum free T4 and serum TSHR-SAb concentrations were higher in the postpartum-exacerbation group.
| Table. Features of Thyroid Dysfunction in Pregnancies Followed by Postpartum Thyroiditis or Postpartum Exacerbation of Graves’ Hyperthyroidism in Women with Graves’ Hyperthyroidism before Pregnancy. | ||
Postpartum Thyroiditis (n=17) |
Postpartum Exacerbation (n= 11) |
|
| Time of onset (mo) | 4.5 |
5.2 |
| Serum free T4 (ng/dl) | 2.8 |
3.9 |
| Serum TSHR-SAb (IU/L) | 1.4 |
72.5 |
The conclusions of the study. Women with hyperthyroidism in the past or during pregnancy may have either postpartum thyroiditis or postpartum exacerbation of Graves’ disease.
The original article. Tagami T, Hagiwara H, Kimura T, Usui T, Shimatsu A, Naruse M. The incidence of gestational hyperthyroidism and postpartum thyroiditis in treated patients with Graves’ disease. Thyroid 2007;17:767-72.
 Next Article: Patients with silent (painless) thyroiditis may have multiple recurrences |
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| Thyroid Digest Index | | | November 2007 Thyroid Digest |
