TFT patterns that were difficult to interpret and required more clinical information, including whether specimens were from patients being treated for thyroidal illness, nonthyroidal illness, subacute thyroiditis, T4 protein-binding abnormalities, medication use, or possible interference, were observed for about 6.9% of 20,469 specimens with all three TFTs. The gene discussed is CD4; the disease is subacute thyroiditis.