Thyroid Hemiagenesis With Subclinical Hyperthyroidism: An Unusual Association

A 21-year-old man was referred to our hospital for the evaluation and treatment of simple goiter. The patient's physical examination was normal except for a palpable left thyroid lobe (grade 1b). All the laboratory investigations and thyroid function tests were normal, except for a subnormal serum thyroid stimulating hormone level. The patient had no complaint of hyperthyroidism. Both the serum antibodies (antithyroglobulin and antithyroid peroxidase) were negative. Thyroid ultrasonography revealed the agenesis of the left lobe and isthmus of the thyroid. Thyroid scan with Tc-99 m pertechnate showed the absence of the left lobe and isthmus and diffusely enlarged right lobe hyperplasia. A follow-up of 6 months was carried out without any medication. Post follow-up, the thyroid function tests were still consistent with subclinical hyperthyroidism. In this report, we have described the case of a patient with thyroid hemiagenesis associated with subclinical hyperthyroidism and goiter.