Transient postpartum hypothyroidism: fourteen cases with autoimmune thyroiditis.

Twenty-five episodes of postpartum primary hypothyroidism were observed in 23 patients without thyroid hormone treatment: three were cases of irreversible hypothyroidism and the others were of transient hypothyroidism. The characteristics of transient postpartum hypothyroidism deduced by serial observations on 14 patients were [1] a high incidence of previous goiter; [2] thyroid enlargement at 1/2 to 4 months postpartum; [3] hypothyroidism at 3 to 5 months postpartum; [4] spontaneous recovery at 5 to 10 months postpartum; [5] high titers of antithyroid microsomal antibodies; and [6] persistence of small goiter. Transient postpartum hyperthyroidism before the occurrence of hypothyroidism and the recurrence of transient postpartum hypothyroidism were observed during two consecutive postpartum periods in two patients. Transient hypothyroidism was also observed in two patients after abortion. Fourteen of the 23 patients first noticed thyroid abnormality after delivery. These changes seem to be induced during the course of autoimmune thyroiditis by the immunologic changes occurring after delivery.