| 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.
|
| 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 common is postpartum thyroiditis?
In the United Status, postpartum thyroiditis occurs in approximately
5- 10% of women. The incidence can be greater in certain high-risk
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 post-partum 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.
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.
|
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