The Journal of Clinical Endocrinology & Metabolism · 1992 · 36 citations · 0 references
MedicineEndocrinologyPharmacologyBone MetabolismCalcium HomeostasisMineral MetabolismCalcium MetabolismEndocrine Regulation Of CalciumParathyroid DisordersParathyroid Gland PhysiologyParathyroid Hormone PhysiologyParathyroid Hormone RegulationHypercalcemia Of MalignancyHypercalcemia TreatmentParathyroid Cell FunctionParathyroid DysfunctionParathyroid Hormone BiologyParathyroid Hormone ResponseParathyroid Hormone-related Peptide TestingTumor-induced Hypercalcemia
The effect of lowering ionized calcium on circulating parathyroid hormone (PTH) and parathyroid hormone-related protein (PTHrP) was assessed in twenty patients with hypercalcemia of malignancy following treatment with Pamidronate Disodium. Ionized calcium levels fell rapidly in all treated patients. PTH concentrations were initially suppressed below normal in 18 patients, but rose from 0.48 +/- 0.42 pmol/L to 3.63 +/- 3.13 pmol/L (p less than 0.01) after treatment, reaching higher than normal values in some patients even in the presence of persistent hypercalcemia. PTHrP concentrations did not change significantly after treatment. These findings are consistent with an increased sensitivity of parathyroid tissue to changes in ionized calcium following prolonged exposure to hypercalcemia. Regulation of tumor secretion of PTHrP by calcium was not apparent within the range of calcium concentrations in this study.