Postpartum lymphocytic thyroiditis. Prevalence, clinical course, and long-term follow-up.

A group of 238 women were surveyed for thyroid disease at six and 12 weeks post partum. Twenty-seven (11.3%) of 238 entered into the study were found to have thyroid disease. Fifteen (56%) of 27 had positive microsomal hemagglutinin antibody titers. A spectrum of thyroid disease was found: persistent hypothyroidism (two patients), transient thyrotoxicosis followed by persistent hypothyroidism (one) or transient hypothyroidism (three), euthyroid goiter (five), transient thyrotoxicosis (seven), transient hypothyroidism (three), high-normal thyroxine levels (five), and low-normal thyroxine levels (one). All nine patients who underwent biopsy had active lymphocytic thyroiditis. Three-year follow-up of 25 of the 27 affected individuals revealed that 12 (48%) still had thyroid disease. This study demonstrates that there is a high incidence of postpartum thyroid disease, usually of a transient nature, and that only about one fourth of the cases are detected or clinically obvious.