Scintigraphic Profile of Thyrotoxicosis Patients and Correlation with Biochemical and Sonological Findings

Thyrotoxicosis is a spectrum of disorder with a rather common clinical presentation with different aetiologies. The aetiological diagnosis is important as the management differs. It is essential to accurately diagnose the cause before starting treatment. Scintigraphy of thyroid helps in differentiating accurately the various causes. USG is routinely being advocated and T3/T4 ratio has also been used.

This study aims to evaluate the scintigraphic profile of thyrotoxicosis patients and to correlate biochemical and USG findings with scintigraphy.

A total of 60 newly diagnosed thyrotoxicosis patients based on biochemical reports were included in the study. They underwent further evaluation with ultrasonography and 99mTc scintigraphy.

Of 60 patients of thyrotoxicosis, 45 cases were of Grave's disease, 10 cases were of thyroiditis and five cases were of Toxic Multinodular Goiter (MNG). The clinical characteristics were helpful in establishing the diagnosis in only six (10%) patients who presented with classic features of Grave's disease with ophthalmopathy. T3/T4 ratio greater than 20 was seen only in 29 (66%) patients of Grave's disease and also in three (33.33%) of thyroiditis patients. USG had a sensitivity and specificity of 81.82% and 93.75% in diagnosing Graves' disease and 100% and 82.4% in diagnosing thyroiditis respectively.

Clinical findings do not help in accurately delineating aetiological diagnosis of thyrotoxicosis. Serum T3/T4 ratio when used as a criterion has marked overlap between the various conditions causing thyrotoxicosis. USG has reasonable sensitivity however, misses many cases of early Grave's disease. Follow up scintigraphy helps in a small population with resolving thyroiditis or early Grave's disease where the initial scintiscan is normal or inconclusive.