Homologous radioimmunoassay for human parathyrin (residues 53-84).
We describe a sequential saturation double-antibody radioimmunoassay for carboxyl-terminal fragments of human parathyrin (hPTH) in serum. Standards are prepared with synthetic hPTH (residues 53-84) in hPTH-free serum. Antisera are obtained by immunizing guinea pigs with partly purified hPTH extracted from adenomatous glands. Tracer is prepared by labeling hPTH (53-84), presumably at the histidine residue, with 125I by the Chloramine T method at pH 8.6. Dilution curves for hPTH extracted from adenomas are superimposable on dilution curves for the synthetic 53-84 fragment. Dilution of sera from hyperparathyroid patients showed linearity of response with concentration in the present assay, but non-linearity in the heterologous radioimmunoassay. In contrast to the heterologous system, which discriminated 28 of 32 patients with primary hyperparathyroidism from 32 normals (normal range: undetectable to 54 pmol/L, omitting the highest and lowest values from controls), the present assay separated these groups without overlap.
D002118:Calcium / Q000097:blood / Q000494:pharmacology; D006801:Humans; D006961:Hyperparathyroidism / Q000097:blood*; D010281:Parathyroid Hormone / Q000097:blood*; D010446:Peptide Fragments / Q000097:blood*; D011863:Radioimmunoassay; D012015:Reference Standards
D010281:Parathyroid Hormone; D010446:Peptide Fragments; C035453:parathyroid hormone (53-84); D002118:Calcium