Thyroid Hormone Autoantibody (THAA)

autoantibodies against thyroid hormones (THAb) are the rarest thyroid antibodies . The overall prevalence of THAb among European consecutive patients attending thyroid clinics is 149 in 369,000 or 0.04% . Their rate of detection does not increase if they are searched in the isolated Ig fraction of serum rather than in serum , confirming that their rarity is real.

According to a European survey , THAb against T₃, against T₄, and against both accounted for 51%, 28%, and 21% of the cases, respectively. THAb coexisted with antibodies to thyroglobulin (TgAb) or Ab to microsomes, now called thyroid peroxidase (TPOAb), in 46% and 6% of patients, respectively. THAb have been reported to be of the IgG class virtually always, because this is the class typically sought. Thyroid hormone autoantibodies (THAA) disrupt the equilibrium between thyroid hormones and their binding proteins.