Multiple Immunoreactive Molecular Forms of Parathyroid Hormone in Human Serum

Abstract

Sera from patients with various forms of hyperparathyroidism were concentrated and fractionated on Bio-gel P-10 columns. Eluted fractions were assayed for immunoreactive PTH. In addition to glandular PTH, two smaller fragments were identified (mol wt 7000–7500 and 4500–5000, respectively). Glandular PTH and fragments differed in their immunologic and kinetic properties. The results appear to explain divergent results reported from various laboratories in the application of the immunossay of PTH to clinical investigation.