thermal amplitude (medical) thermal amplitude (medical) thermal amplitude or thermal range refers to the temperature range in which a cold autoantibody or cold-reacting alloantibody binds to its antigen. cold antibodies that can bind to antigen above 30 °c (86 °f) are considered potentially clinically significant and may lead to disease that occurs or worsens on exposure to low temperatures. the closer the thermal range comes to core body temperature (37 °c or 99 °f), the greater the chance that the antibody will cause symptoms such as anemia or raynaud syndrome. antibodies that are only reactive at temperatures below 30 °c (86 °f) are generally considered unlikely to be clinically significant.