SIGNIFICANCE OF PARATHYROID HORMONE-RELATED PROTEIN AS A FACTOR STIMULATING BONE-RESORPTION AND CAUSING HYPERCALCEMIA IN MYELOMA

Elevated levels of parathyroid hormone-related protein (PTHrP) in hype rcalcemic myeloma patients were demonstrated in recent reports, sugges ting that PTHrP behaves as a humoral mediator of hypercalcemia in myel oma, Herein we describe a hypercalcemic myeloma patient with a high se rum PTHrP level, Moreover, the PTHrP level in the supernatant of bone marrow aspirates was about two-fold of that in serum. Reverve transcri ptase-polymerase chain reaction analysis showed PTHrP m-RNA in bone ma rrow containing myeloma cells. After chemotherapy, the concentrations of calcium and PTHrP decreased and PTHrP mRNA in bone marrow became un detectable, We conclude that PTHrP released by myeloma cells acted as the main bone resorption stimulating factor in this case. Am. J, Hemat ol, 59:168-170, 1998, (C) 1998 Wiley-Liss, Inc.