Analysis of parathyroid hormone in bovine parathyroid cysts

Parathyroid cysts were found in 2-5% of beef steers and heifers while collecting parathyroids at a local abattoir. The cyst fluid contained parathyroid hormone (PTH), averaging 15 ng/ml of fluid. Reversed-phase high-performance liquid chromatographic (HPLC) analysis of the fluid using an acetonitrile-trifluoroacetic acid solvent system, followed by carboxyl-terminal specific PTH radioimmunoassay of the eluant fractions, revealed two major peaks of PTH immunoreactivity. The first eluted at approximately 25% acetonitrile, a position similar to the commercially available human carboxyl terminal fragment of PTH-(39-84). The second peak, at approximately 37% acetonitrile, corresponded to the elution position for bovine PTH-(1-84). The cyst fluid was tested for enzyme activity by incubation of 125I-labeled bovine PTH with cyst fluid for 30 minutes at 37 degrees C, which resulted in no fragmentation of the labeled peptide. Immunohistochemistry of the cells lining the parathyroid cyst indicated that they contained PTH.