Hemiagenesis of the thyroid gland.

Three patients with hemiagenesis of the typhoid gland are described. One was clinically euthyroid, whereas the other two were more unusual in that one had coincident Graves' disease with thyrotoxicosis, and one had primary myxodema. In all three cases diagnosis of hemiagenesis was established by the administration of thyroid-stimulating hormone (TSH). The literature on hemiagenetic thyroid glands with and without associated thyroid disease is reviewed. Although the anomaly is uncommon, awareness and recogniton of its existence may clarify an otherwise puzzling clinical thyroid evaluation, and thus possible avert an unnecessary surgical procedure.