Radioimmunoassay for partially degraded thyrotropin

A radioimmunoassay for partially pepsin degraded bovine thyrotropin (bTSH) was developed and used to examine human thyrotropin (hTSH) preparations and sera obtained from patients with Graves' ophthalmopathy for the presence of cross-reactivity. As little as 4 microunits of the hTSH (68/38) reference preparation produced inhibition of binding in the radioimmunoassay, but none of the sera obtained from patients with Graves' disease (n = 26) contained detectable cross-reactivity. These data indicate that there is a substantial amount of partially degraded thyrotropin in human pituitary extracts, but none detectable in the sera of patients with Graves' ophthalmopathy.