Hashimoto's thyroiditis

Postpartum thyroiditis is a syndrome characterized by transient thyrotoxicosis, with a low thyroid radioactive iodine uptake followed by a hypothyroid phase. The syndrome occurs during the first year after delivery. Normal thyroid function is restored in most patients. Roti and Emerson review postpartum thyroiditis to delineate the pathophysiology, diagnosis and treatment.

In most studies, postpartum thyroiditis has been reported to occur in 3.9 to 8.2 percent of women. However, a marked variability occurs in the incidence rate. Some regions of Britain have an incidence rate as high as 16.7 percent, while New York and Thailand have reported rates of less than 2 percent.

The clinical course of postpartum thyroiditis consists of three sequential phases: thyrotoxic, hypothyroid and recovery. The syndrome usually presents with a thyrotoxic state that occurs one to three months after delivery and lasts for one to two months. Postpartum thyroiditis is distinguished from Graves' disease by a decreased radioactive iodine uptake. Thyrotoxicity is followed by a hypothyroid state that appears three to six months after delivery. Both thyrotoxic and hypothyroid states have few symptoms, except for fatigue; thus, the condition may go unrecognized. The most common physical sign in both stages is a painless enlargement of the thyroid gland.

Women with antithyroid antibodies or a history of goiter are more likely to develop postpartum thyroiditis. Many patients have underlying Hashimoto's thyroiditis, and women with Graves' disease develop postpartum thyroiditis more frequently than women in the general population. Thyroid antibody titers decrease during pregnancy with a nadir at term and a rise after delivery, possibly explaining the temporal relationship between delivery and postpartum thyroiditis. A strong correlation is not apparent between postpartum thyroiditis and other autoimmune disorders, such as rheumatoid arthritis and Sjogren's syndrome.

In a woman presenting with fatigue, palpitations, emotional lability or thyroid enlargement during the first year after delivery, postpartum thyroiditis should be considered. The usual thyroid screening tests, as well as radioactive iodine uptake scan and antithyroid antibody titers, should be performed. No therapy is warranted during the thyrotoxic phase, except beta blockers for symptomatic relief. During the hypothyroid stage, thyroid replacement should only be given if symptoms are severe. Many women are in the recovery phase when their symptoms are recognized.

All women with postpartum thyroiditis should have long-term follow-up, because hypothyroidism may recur in up to 23 percent of patients. Recurrent hypothyroidism may develop two to four years after the initial presentation. Iodine may also increase the incidence of hypothyroidism, so excess iodine intake should be discouraged in patients with postpartum thyroiditis. (Journal of Clinical Endocrinology and Metabolism, January 1992, vol. 74, p. 3.)

COPYRIGHT 1992 American Academy of Family Physicians
COPYRIGHT 2004 Gale Group