Abstract 117: Hemiagenesis of thyroid gland with Grave's disease: A rare case report

Background: Hemiagenesis of thyroid gland is a rare congenital disorder. It can be associated with a variety of thyroid disorders. Case Report: A 35 year oldfemale presented withsignificant unintentional weight loss, difficulty in swallowing and tremors of hands from 2 months duration. Herserum TT3, TT4 levels were elevated andserum TSH was suppressed. Tc99 scan of thyroid gland showed an increased trapping function in the isthmus and left lobe of thyroid likely toxic adenoma. She was started on carbimazole. On follow up, a goiter was palpable on left side and right lobe of thyroid was not palpable. An USGthyroid gland was done in which right lobe of the thyroid gland was not visualized. There were 2 isoechoic nodules in the left lobe of thyroid 5 x 3 mm and 5 x 4 mm with a hypoechoic rim (TIRADS 2 score). As there was no evidence of tracer uptake in the region of right lobe of thyroid gland with increased homogenous tracer uptake (uptake at 20 mins- 4.7%) in the isthmus and left lobe of thyroid gland, a possibility of Graves' disease was considered. TSHR Antibody testing was planned on follow up. Discussion: Thyroid hemiagenesis is a rare congenital disorder in which one lobe of the thyroid gland fails to develop while the other lobe develops normally with or without an isthmus. The prevalence of thyroid hemiagenesis is reported to vary from 0.05% to 0.5%. Most of them are euthyroid but may be associated with hyper- or hypothyroidism. Left lobe hemiagenesis is common with left to right hemiagenesis ratio of 4:1. Various extrathyroidal abnormalities can coexist with thyroid hemiagenesis like parathyroid adenoma or hyperplasia, congenital disorders etc. Conclusions: Graves' disease with thyroid hemiagenesis must be considered in cases of unilateral homogenous increased tracer uptake on thyroid scintiscan. Thyroid ultrasonography is a non-invasive, inexpensive, and valuable modality for a quick diagnosis of thyroid hemiagenesis and differential diagnosis from other causes.