Thyroidal hemiagenesis.

Three cases of thyroidal hemiagenesis have been reported. The patients were euthyroid and presented with adenomatous goiters; one uninodular and the others multinodular in the contralateral lobe. In two cases the diagnosis was established by the thyroid stimulation test and confirmed at operation. In one case, this test was not performed and the hemiagenesia was discovered at routine surgical exploration of the scintigraphically absent lobe. From our cases and review of the literature we have concluded that the anomaly is usually discovered while searching for a contralateral pathologic abnormality, a thyroid stimulation test is essential for a preoperative suspicion, it occurs more frequently among women and in the left lobe, and ours are the first cases reported from Spain.