Thyroid hemiagenesis with postpartum silent thyroiditis.

A 28-year-old woman with thyroid hemiagenesis, who had been diagnosed as having Graves' disease, became pregnant during the course of methimazole treatment. The treatment was terminated in the second trimester. She delivered a normal infant at full term. She became thyrotoxic 3 months after the delivery, hypothyroid 6 months after the delivery, and finally euthyroid 11 months after the delivery without undergoing any treatment. This clinical course indicates that she developed silent thyroiditis after the delivery. A diagnosis of thyroid hemiagenesis was made on the basis of ultrasonography of the thyroid and 99mTc-pertechnetate thyroid scintiscan.