Hemiagenesis of the thyroid gland and T3 hyperthyroidism.

Introduction Thyroidal hemiagenesis is a congenital anomaly in which one lobe of the thyroid fails to develop, and was first described by Marshall in 1895. The more recent literature suggests that aplasia of one lobe of the thyroid gland is rare and is diagnosed only because of the concurrence of hyperthyroidism, adenocarcinoma and colloid goitre (Burman, Adler and Wartofsky, 1975; Hamburger and Hamburger, 1970). Although hemiagenesis of the thyroid gland is a benign condition, lack of awareness of its existence may lead to an incorrect diagnosis. The purpose of this report is to describe a patient with hemiagenesis of the thyroid gland who also presented with T3 toxicosis. To the authors' knowledge this is the first such report in the literature.