We have seen several people here with precisely what they are talking about here - blood test results that appear not to make any sense.
Can't actually remember anyone ever posting that they have been tested for thyroid hormone antibodies (that is, antibodies to T4 or T3), though we have seen a few who might have had antibodies to TSH.
Probably one of those things that everyone thinks is really, really rare until someone starts testing lots of people.
AACE Clin Case Rep. 2017 Winter;3(1):e22-e25. doi: 10.4158/EP151142.CR.
Diagnostic Dilemma in Discordant Thyroid Function Tests Due to Thyroid Hormone Autoantibodies.
Srichomkwun P1, Scherberg NH1, Jakšić J2, Refetoff S3.
1Department of Medicine, The University of Chicago, Chicago, Illinois.
2Department of Pediatrics, General Hospital, Sibenik, Croatia.
3Department of Medicine, The University of Chicago, Chicago, Illinois; Department of Pediatrics and the Committee on Genetics, The University of Chicago, Chicago, Illinois.
Assay interference could be the cause of abnormal thyroid function tests. Early recognition prevents inappropriate patient management. The objective of this report is to present a case with discordant thyroid function tests in different thyroid assay platforms due to thyroid autoantibodies.
We present a case her family, laboratory data and methods that investigate immunoassay interference.
A 21-year-old woman with autoimmune thyroid disease was treated for hypothyroidism with levothyroxine and noted to have elevated total and free thyroxine, free triiodothyronine but normal thyroid-stimulating hormone. Repeat thyroid function tests using different platforms revealed discrepant results. Further investigation showed that the patient had positive thyroid hormone autoantibodies (THAAbs).
We demonstrates abnormal thyroid function tests caused by THAAbs. The latter were the cause of interference with assays resulting in discrepant test results inconsistent with the clinical presentation. Early recognition would prevent inappropriate patient management.
euthyroid hyperthyroxinemia; thyroid function test; thyroid hormone autoantibodies