Bioassay Test Helps Diagnose Graves' Disease

A new blood testing method specifically detects thyroid-stimulating immunoglobulins (TSIs), used to help identify Graves' disease.

The Thyretain TSI Reporter bioassay provides laboratories with the ability to test for TSI in the bloodstream using standard laboratory equipment, and unlike other nonspecific thyroid-related assays, does not require the use of radioactivity, and also eliminates ambiguity of test results that can be confounded by the presence of non-TSI autoantibodies. The kit includes a genetically engineered cell line that produces the reporter enzyme luciferase in response to specific TSI binding, and the amount of luciferase produced is then rapidly detected using a luminometer. The bioassay offers greater specificity because it only detects the TSI present in a patient's serum, aiding in a more accurate early diagnosis of Graves' disease. The Thyretain TSI Reporter bioassay was developed by Diagnostic Hybrids (Athens, OH, USA), and has been approved by the U.S. Food and Drug Administration (FDA).

"When used earlier when hyperthyroidism is first suspected, this assay may provide primary care physicians and patients alike reliable diagnostic information when classic symptoms of goiter or thyroid-related eye disease [ophthalmopathy] are absent,” said Jeff Houtz, senior product manager for Thyretain at Diagnostic Hybrids.

"Initial symptoms for thyroid disorders can often be nonspecific. By finding TSIs in patient serum, Thyretain is a rapid and reliable bioassay that provides a definitive assessment that could lead to earlier diagnosis of Graves' disease and better patient management,” said Frank Schwartz, M.D., a professor of endocrinology at the Ohio University College of Osteopathic Medicine (Northfield, USA).

Graves' disease is an autoimmune disease that most commonly affects the thyroid, frequently causing it to enlarge to twice its size or more (goiter) and become overactive, causing overstimulation of the thyroid gland and low thyroid-stimulating hormone (TSH) levels, a condition known as hyperthyroidism. Related symptoms such include increased heartbeat, muscle weakness, disturbed sleep, and irritability. It can also affect the eyes, causing bulging eyes (exophthalmos). It affects other systems of the body, including the skin, heart, circulation, and nervous system. Eighty percent of Graves' disease cases occur in women, and can be difficult to diagnose since symptoms vary greatly and often mimic other illnesses.

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