Development of an Homologous Radioimmunoassay for the Synthetic Amino Terminal (1-34) Fragment of Human Parathyroid Hormone Using Egg Yolk-Obtained Antibodies

Abstract An homologous radioimmunoassay for the synthetic 1–34 amino terminal fragment of human parathyroid hormone (hPTH) was developed using antibodies obtained from yolk of eggs layed by an immunized chicken. The I labelled 1–34 hPTH peptide was purified by cation-exchange chromatography which provided a highly stable preparation. The specificity of the assay showed a cross-reactivity of 50% with the 1–34 hPTH (code 81/574) preparation and 27% with the 1–84 hPTH (code 79/500) preparation, when compared with the 1–34 hPTH from Bachem that was used for immunization and labelling. The minimal detectable dose of the assay was 10 pmol/1; in 69 healthy controls the values obtained ranged from < 10 to 28 pmol/l and in 14 patients with surgically proven primary hyperparathroidism 10 to 519 pmol/l.