Sephadex gel filtration analysis of immunoreactive thyrotrophic hormone in human urine

SUMMARY To assess whether urinary immunoassayable thyroid-stimulating hormone (TSH) differed from pituitary and serum TSH, urinary concentrates from two hypothyroid subjects were analysed by Sephadex G-100 gel filtration. The elution profiles, measured by radioimmunoassay, were then compared with those of neat sera from hypothyroid patients and human pituitary TSH preparations. The pituitary preparations and the hypothyroid serum were eluted as a comparable single symmetrical peak corresponding to that obtained from a highly purified radio-iodinated human TSH of pituitary origin; no evidence of 'big' TSH emerged. In contrast, however, the material eluted from the hypothyroid urine concentrates not only revealed an asymmetrical peak corresponding to that described above but several other minor peaks eluting later and probably corresponding to fragments of TSH. When human pituitary TSH was infused into two normal subjects, gel filtration analysis of concentrates from urinary samples obtained during and at fixed periods after the infusion revealed a single peak during the infusion but more peaks appeared with the later samples.