Postpartum Thyroiditis: Not Just a Worn Out Mom

Katherine Pereira; Ann J. Brown

Disclosures

Journal for Nurse Practitioners. 2008;4(3):175-182. 

In This Article

Clinical Course

Clinically, the hyperthyroid stage of PPT lasts about 8 weeks and is self-limited. The subsequent hypothyroid stage of PPT lasts a bit longer, on average 4 to 6 months.[1] The hypothyroid phase is then followed by a return of normal thyroid function. Twenty to thirty percent of women with PPT will remain permanently hypothyroid instead of showing the typical pattern of resolution.[1] Long-term follow-up of women with PPT also reveals that permanent hypothyroidism is more likely to develop in these women. Twelve to sixty-one percent will be hypothyroid 3 to 9 years following an episode of PPT.[7] Thus, these women should be considered to be at higher risk of developing hypothyroidism at some point in life. Factors that appear to increase the risk of persistent hypothyroidism include delivery of female infant, higher levels of TSH during the hypothyroid phase, and increased maternal age.[3]

Prospective studies have been conducted in large groups of pregnant women to identify risk factors for PPT. Pregnancy is associated with significant changes in immune function. For instance, there is normally an increase in CD4, CD25, and regulatory T cells. These changes result in reduced T-cell and B-cell function, perhaps to allow for tolerance of the immunologically foreign fetus. Thyroid peroxidase antibody levels typically fall during pregnancy. This is thought to be related to both elevated progesterone and estradiol levels that are seen in pregnancy.[1] T cells and B cells return to baseline function after delivery and play a key role in the lymphocytic infiltration of the thyroid gland seen in PPT. Numerous studies have shown that women who go on to develop PPT have high levels of circulating antithyroid antibodies early in pregnancy.[9,14] After delivery, there is an increase in autoantibody secretion, along with decline in estrogen levels, and there can be exacerbation of autoimmune-mediated illness such as PPT.

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