False Positive Elevations of T3 after Viral Infections
Mar
4
Written by:
3/4/2012
Autoantibodies may develop against thyroid hormone and also TSH. Hormone antibodies falsely elevate blood levels, especially in total T3 levels, because of their ability to react with binding proteins as if they were thyroid hormone molecules.
While the presence of hormone antibodies is long known, they're generally considered rare and only tested for when lab results appear erratic or confusing. When false elevations are suspected FT3 levels by dialysis, are used to filter out interfering antibodies.
Studies show that elevations of total T3 are often seen in active viral infections, especially infections with EBV. Latent infections and re-activated viral infections can cause transient increases in levels of circulating hormone antibodies. Elevations of T3 caused by hormone antibodies have been reported in Graves' disease, Hashimoto's thyroiditis, Sjogren's syndrome and rheumatoid arthritis and in patients on interferon. Antibodies to thyroxine (T4) may also occur and are suspected when T4 and FT4 levels appear erratically elevated.
Resource:
Shimon I, Pareinte c, Shlomo-David J, et al. 2003. "Transient elevation of triodothyronine caused by triidothyronine autoantibody associated with acute Epstein-Barr virus infe tion. Thyroid 13;211-215.