Thyroid-stimulating antibodies: action and diagnostic relevance
THE CONTEXT
Thyroid-stimulating antibodies activate thyroid follicular cells through TSH receptors and account for most thyrotoxicosis outside autonomous toxic nodules.
Mechanism and duration
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These antibodies are IgG immunoglobulins that bind to and activate thyroid-stimulating hormone (TSH) receptors on the follicular cell membrane.
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Their action lasts 16–24 hours, compared with 1.5–3 hours for TSH.
Clinical significance
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They are responsible for virtually all cases of thyrotoxicosis not caused by autonomous toxic nodules.
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Serum concentrations are very low, and antibody measurement is not essential for making the diagnosis.