Abstract
We have produced an antiserum to porcine parathyroid hormone (PTH) which distinguishes between the PTH in human hyperparathyroid serum and that in extracts of parathyroid adenomata. The PTH secreted into the medium by parathyroid adenoma slices in culture reacts with this antiserum in the same way as the PTH in human hyperparathyroid serum, but extraction of the same serum by a conventional procedure used for the extraction of glandular tissue converts the serum hormone to a species which reacts more like hormone extracted from adenomata. The results suggest that we have immunologically identified a native molecular species of PTH, that the antiserum used recognizes primarily this species in human hyperparathyroid serum, and that the PTH extracted from parathyroid adenomata is immuno-chemically altered.