Falsely positive bovine TSH radioimmunoassay responses in sera from patients with thyroid cancer

We previously reported a high incidence of material similar in immunological activity to bovine TSH in patients with thyroid cancer. Further investigation has revealed that these results were falsely positive. They can be attributed in part to previous immunization of some patients with injections of bovine TSH, and in part to nonspecific protein effects on the solid-phase radioimmunoassay system, which requires not only a constant protein concentration, but also a constant protein composition of the reaction medium.