source: Endocrine Society
Albert Hsieh, Stephen Morris Twigg, Elizabeth Lian Chua
The diagnosis of Graves’ disease (GD) is traditionally based on the clinical features of persisting hyperthyroidism, enlarged thyroid gland, and often the presence of ophthalmopathy. However, when the clinical presentation of thyrotoxicosis is not diagnostic of GD, the 2011 American Thyroid Association guideline recommends “a radioactive iodine uptake scan should be performed”. Although it is long recognized that Thyrotropin (TSH) receptor antibody (TRAb) is the pathogenic agent of thyrotoxicosis, measurement of TRAb for diagnostic purpose is only recommended “when the thyroid scan and uptake are unavailable or contraindicated.” With the availability of highly sensitive TRAb assays, we performed an audit on the Royal Prince Alfred Hospital (RPAH) Thyroid Clinic encounters between years 2000 to 2012, examining the diagnostic utility of TRAb versus thyroid scan in confirming GD.
Thyroid scans were performed using technetium-99m sodium pertechnetate isotope. Positive thyroid scan was defined as diffuse thyroid uptake of the tracer and thyroid activity not being low. TRAb were analyzed within the first 3 months of hyperthyroidism and the analysis was performed on newer generation TRAb assays (BRAHMS TRAK human RIA & Roche Elecsys Anti-TSHR assay). TRAb was considered positive if the antibody was above the upper limit of the population reference range.
Royal Prince Alfred Hospital, Australia