By Simeon Margolis, M.D., Ph.D.
During the postpartum period, about 1 in 15 women develops thyroiditis, a transient autoimmune inflammation of the thyroid gland marked by an accumulation of certain white blood cells in that gland. (The immune system usually guards against foreign invaders—for example, by destroying dangerous bacteria—but in an autoimmune disorder, the immune system inappropriately targets and damages some of the body's own healthy cells.)
In about one quarter of these women, the disorder begins 1 to 4 months after delivery. Mild symptoms caused by an overactive thyroid (hyperthyroidism) last for 2 to 8 weeks, followed by an underactive thyroid (hypothyroidism) that lasts for 2 weeks to several months. About half of the women with postpartum thyroiditis only develop the symptoms of hypothyroidism, which begins 2 to 6 months after delivery. In most of these women, the hypothyroid symptoms disappear within a year or less, but about a third end up with permanent hypothyroidism that requires treatment.
Women with a hyperthyroid phase have mild symptoms such as irritability, anxiety, muscle weakness, tremor, rapid heart beat, and palpitations. Symptoms of hypothyroidism—fatigue, sluggishness, and dry skin—are also usually mild. In some studies, postpartum depression was associated with or aggravated by the hypothyroidism.
Women need to be aware that postpartum thyroiditis can be difficult to diagnose and may require referral to an endocrinologist.
Although most women with this disorder require no treatment, if troublesome symptoms appear, they can be controlled: hyperthyroid symptoms with a beta-blocker, and hypothyroid symptoms through temporary replacement of thyroid hormone. Women with postpartum hypothyroidism need some regular follow-up in case hypothyroidism persists.