A Temporary Thyroid Disorder
By Elaine Moore
Postpartum thyroiditis (PPT) refers to a painless inflammatory thyroid disorder affecting up to 7 percent of all pregnancies. PPT typically causes a transient condition of subclinical or overt hyperthyroidism lasting several weeks to several months. In PPT, the period of hyperthyroidism resolves and is followed by several weeks of euthyroidism (normal thyroid function).
Then, as the thyroid gland exhausts its stores of thyroid hormone, the period of euthyroidism is followed by a 3-5 month period of subclinical or overt hypothyroidism. In some cases, multiple alternating cycles of thyroid disease can occur. PPT typically occurs within 12 months of childbirth, miscarriage, or abortion and spontaneously resolves within 12-18 months following the onset of symptoms.
In rare cases, women develop long-term hypothyroidism after PPT resolves. In this case, the women generally require lifelong thyroid hormone replacement therapy.
Rarely, hypothyroidism after childbirth is caused by Sheehan's syndrome, also called postpartum hypopituitarism, a disorder of pituitary gland insufficiency. This condition may occur in women who have severe blood loss during childbirth resulting in damage to the anterior pituitary gland. PPT can be confused with Sheehan’s Syndrome.
The Autoimmune Connection
PPT is regarded as a form of Hashimoto’s thyroiditis. Patients with PPT usually have mild to moderate elevations of TPO and thyroglobulin antibodies, which are much lower than the marked thyroid antibody elevations seen in Hashimoto’s thyroiditis.
Postpartum thyroiditis is usually diagnosed during the thyrotoxic phase of the disorder when thyroid hormone levels are elevated. Symptoms of hyperthyroidism can occur, including weight loss, depression, anxiety, nervousness, elevated heart rate, heat intolerance, headache, nausea, and palpitations. If diagnosis occurs during the hypothyroid phase of PPT, symptoms of hypothyroidism, such as weight gain, depression, constipation, and joint pain are more likely to occur.
In postpartum thyroiditis, thyroid function tests are used to determine thyroid status. Tests for thyroglobulin and TPO antibodies may show mild elevations and tests for TSI are negative. The RAI-uptake test result is low making it easy to differentiate from Graves’ disease, a condition in which the uptake is elevated 3-5 times the normal range. ♦
© 27 May 2006 Copyrighted by Elaine Moore