Letters Section Editor: Robert M. Golub, MD, Senior Editor.
In Reply: Drs Völzke and Hoffmann raise questions about the cutoff point we used for determining TPOAb positivity in our participants. Setting of a defined cutoff point for thyroid autoantibody assay is a point of debate among clinical researchers. Our decision to use a 10-IU/mL value was based only in part on this being the value recommended by the manufacturer of the TPOAb enzyme-linked immunosorbent assay.1 More importantly, this cutoff value has been shown to be highly specific in terms of diagnosing autoimmune thyroid diseases (AITDs), with a specificity as high as 94.9%.2
Imaizumi M, Ashizawa K, Akahoshi M. Radiation Exposure and Thyroid Disease in Hiroshima and Nagasaki Atomic Bomb Survivors—Reply. JAMA. 2006;296(5):512-513. doi:10.1001/jama.296.5.512-b