Thermal amplitude test.

The thermal amplitude test is performed to determine the reactivity of a cold autoantibody at varying temperatures: 4° C, 22° C, 30° C, and 37° C. Cold autoantibodies that are reactive at temperatures greater than 30° C have the potential to be clinically significant regardless of the antibody titer. Cold antibodies that are reactive at temperatures less than 30° C are not considered to be clinically significant.