Thyroid Scintigraphy of a Rare Case of Left Thyroid Lobe Hemiagenesis With Subacute Thyroiditis.

Thyroid hemiagenesis is a rare developmental anomaly. Patients with thyroid hemiagenesis have higher incidence of coexisting thyroid disorders in the remaining lobe. We present a rare case of a 21-year-old woman with subclinical hyperthyroidism incidentally found to have thyroid hemiagenesis on thyroid 123I-Na scan, which is confirmed on thyroid ultrasound. On scintigraphy, only the right lobe showed activity. Thyroid ultrasound demonstrated that the right lobe was normal without any nodule. The left lobe was not visualized. This patient's thyroid uptake and scan also revealed low uptake in the remaining right thyroid lobe in keeping with subacute thyroiditis.