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Late hypothyroidism is common in women with postpartum thyroiditis

(November 2005)

The background of the study. Postpartum thyroiditis is a disorder that by arbitrary definition occurs within a year after delivery. It is characterized by hyperthyroidism, hypothyroidism, or hyperthyroidism followed by hypothyroidism. The thyroid dysfunction is usually transient, but some women later have hypothyroidism or goiter. In this study, the long-term outcome of women with postpartum hypothyroidism was determined.

How the study was done. The study subjects were 172 women who presented with hypothyroidism an average of 6 months post partum and who had been treated with thyroxine (T4) because they had goiter or symptoms of hypothyroidism. The T4 therapy was stopped after 12 to 84 months (average, 24 months), after which the women were seen and serum thyrotropin (TSH) and free T4 were measured periodically.

The results of the study. The women were followed for 1 to 120 months after T4 was stopped, until either the onset of hypothyroidism or last evaluation. Some women had onset of hypothyroidism within 1 to 2 months after stopping T4, and the number increased continually thereafter; at 60 months, approximately 60 percent of the women had hypothyroidism.

The conclusions of the study. Women with postpartum thyroiditis who have hypothyroidism and are treated with T4 for one or more years often have hypothyroidism later.

The original article. Azizi F. The occurrence of permanent thyroid failure in patients with subclinical postpartum thyroiditis. Eur J Endocrinol 2005;153:367-71.