Plasma parathyroid hormone related-protein levels in patients with cancer, normocalcemic and hypercalcemic

Abstract Hypercalcemia in patients with cancer may reflect the synthesis and secretion into circulation of parathyroid hormone-related protein (PTHrP) produced by the tumor. In the present study, we have measured circulating PTHrP concentrations in healthy subjects and patients using a new immunoradiometric assay (IRMA) that is specific for the 1–86 amino acid sequence of molecule, and in plasma collected with protease inhibitors. Plasma concentrations of PTHrP(1–86) were greater than the detection limit of the assay (0.3 pmol/l) in healthy subjects. All patients with hypercalcemia-associated cancer had PTHrP(1–86) levels significantly greater (median 7.74 pmol/l, P