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Updated: Jul 6, 2026

Generation of a Mouse Spontaneous Autoimmune Thyroiditis Model
Published on: March 17, 2023
Interference in free thyroxine immunoassay
Sujoy Ghosh1, Michael Howlett, David Boag
1The Ayr Hospital, Dalmellington Road, Ayr KA6 6DX, United Kingdom. drsujoyghosh@rediffmail.com
Abstract:
We report two patients who presented with non-specific symptoms of tiredness that prompted their clinician to order a thyroid function test. In both cases, free thyroxine (T4) was reported to be high, with a normal thyroid-stimulating hormone (TSH). Repeated blood tests from the same laboratory using the same assay method yielded similar results. Due to discrepancies between the clinical and laboratory findings, we decided to repeat the blood tests at another laboratory using a different assay method. This revealed normal free T4 and TSH levels, suggesting that heterophile antibodies were interfering with the free T4 assay, leading to clinical confusion.
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