What is postpartum thyroiditis?
Thyroiditis is a general term that refers to “inflammation of the thyroid gland” (see Thyroiditis Brochure); thus, postpartum thyroiditis is thyroiditis that occurs in women after the delivery of a baby. Thyroiditis can cause both thyrotoxicosis (high thyroid hormone levels in the blood) and hypothyroidism (low thyroid hormone levels in the blood). In postpartum thyroiditis, thyrotoxicosis occurs first followed by hypothyroidism.
The thyroid gland is a butterfly-shaped endocrine gland that is normally located in the lower front of the neck. The thyroid’s job is to make thyroid hormones, which are secreted into the blood and then carried to every tissue in the body. Thyroid hormone helps the body use energy, stay warm and keep the brain, heart, muscles, and other organs working as they should.
What causes postpartum thyroiditis?
The exact cause is not known but it is believed to be an autoimmune disease very similar to Hashimoto’s thyroiditis. In fact, these two disorders cannot be distinguished from one another on pathology specimens. As in Hashimoto’s thyroiditis, postpartum thyroiditis is associated with the development of anti-thyroid (anti-thyroid peroxidase, anti-thyroglobulin) antibodies. Women with positive antithyroid antibodies are at a much higher risk of developing postpartum thyroiditis than women who do not have have positive antibodies. It is believed that women who develop postpartum thyroiditis have an underlying asymptomatic autoimmune thyroiditis that flares in the postpartum period when there are fluctuations in immune function.
How comon is postpartum thyroiditis?
In the United Status, postpartum thyroiditis occurs in approximately 5-10% of women. The incidence can be greater in certain highrisk populations (see below).
Who is at risk for developing postpartum thyroiditis?
Any woman with:
- Autoimmune disorders (such as Type 1, or juvenile onset, Diabetes Mellitus)
- Positive anti-thyroid antibodies (risk correlates with antibody levels, the higher the antibody the higher the risk)
- History of previous thyroid dysfunction
- History of previous postpartum thyroiditis (20% of women will have recurrence of thyroiditis with subsequent pregnancies)
- Family history of thyroid dysfunction
What is the clinical course of postpartum thyroiditis?
The classic description of postpartum thyroiditis includes thyrotoxicosis followed by hypothyroidism. Not all women demonstrate evidence of going through both phases; approximately 1/3 of patients will manifest both phases, while 1/3 of patients will have only a thyrotoxic or hypothyroid phase. The thyrotoxic phase occurs 1-4 months after delivery of a child, lasts for 1-3 months and is associated with symptoms including anxiety, insomnia, palpitations (fast heart rate), fatigue, weight loss, and irritability. Since these symptoms are often attributed to being postpartum and the stress of having a new baby, the thyrotoxic phase of postpartum thyroiditis is often missed. It is much more common for women to present in the hypothyroid phase, which typically occurs 4-8 months after delivery and may last up to 9 –12 months. Typical symptoms include fatigue, weight gain, constipation, dry skin, depression and poor exercise tolerance. Most women will have return of their thyroid function to normal within 12-18 months of the onset of symptoms. However, approximately 20% of those that go into a hypothyroid phase will remain hypothyroid.
How is postpartum thyroiditis treated?
Treatment depends on the phase of thyroiditis and degree of symptoms that patients exhibit. Women presenting with thyrotoxicosis may be treated with beta blockers to decrease palpitations and reduce shakes and tremors. As symptoms improve, the medication is tapered off since the thyrotoxic phase is transient. Antithyroid medications (see Hyperthyroid brochure) are not used for the thyrotoxic phase since the thyroid is not overactive.
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The hypothyroid phase is often treated with thyroid hormone replacement (see Thyroid Hormone Therapy brochure). If the hypothyroidism is mild, and the patient has few, if any, symptoms, no therapy may be necessary. If thyroid hormone therapy is begun, treatment should be continued for approximately 6-12 months and then tapered to see if thyroid hormone is required permanently. It is always important to try to discontinue thyroid hormone after postpartum thyroiditis, since 80% of patients will regain normal thyroid function and not require chronic therapy.
Further details on this and other thyroid-related topics are available in the patient information section on the American Thyroid Association website at www.thyroid.org.
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