This is based on 3 aspects of the disease:
1 Clinical Features
Characteristic findings such as lid retraction combined with proptosis and limited motility are highly suggestive of TED, particularly when bilateral.
2 Thyroid Function and Antibody Tests:
Abnormal thyroid function tests (thyroxine and TSH levels) or a history of thyroid dysfunction help confirm the diagnosis, although 10% of TED patients may be euthyroid at onset. The presence of TSH-R antibodies has high sensitivity for active Graves’ disease.
3 Orbital Imaging:
Computerized tomography (CT) or magnetic resonance imaging (MRI) may help confirm the diagnosis, particularly for atypical or uncertain clinical situations. CT scan documents fat or muscle enlargement and apical crowding and allows assessment of bony walls and sinuses for possible surgical decompression. Contrast CT scans may show enhancement of the extraocular muscle sheaths or stranding of surrounding orbital fat in the active inflammatory phase or lucent spaces in the extraocular muscles in the inactive phase. MRI identifies edema within the extraocular muscles on T2 or STIR sequence in active disease.