1211 Randomised double-blind comparison of pamidronate or clodronate for hypercalcaemia of malignancy: Effects on bone metabolism markers

Abstract

New and potentially more specific markers of bone resorption were recently identified: deoxypyridinoline (Dpd), pyridinoline (Pyd) (which are total cross-links) and the C-telopeptide of type I collagen (peptidebound cross-links). We evaluated 32 hypercalcaemic pts. after 48 hr of intravenous rehydration who received either 90mg pamidronate or 1500mg clodronate as a 4 hr infusion. Serum and urine samples were collected at baseline, 2, 4, 7, 14, 21 and 28 days. We measured serum Ca, PO4 and PTH; and in a 2nd voided morning urine sample: urinary calcium (uCa), Dpd, Pyd (both by HPLC) and the C-telopeptide (Crosslaps) by an ELISA assay. Both bisphosphonates were effective treatments for hypercalcaemia, but the duration ofnormocalcaemia was longer after pamidronate (28 vs 14 days, <i>P</i>=0.01). UCa (considered as the standard resorption marker) fell significantly in both arms partially reflecting inhibition of bone resorption, but also an increase in PTH. Dpd, Pyd and C-telopeptide had a significant larger and longer lasting decrease after pamidronate (<i>P</i><0.01). The C-telopeptide fall was significantly larger than Dpd or Pyd fall in both arms (<i>P</i><0.01). C-telopeptide is easier and faster to perform than Dpd and Pyd. The prolonged effect of pamidronate on hypercalcaemia is explained by the longer suppression of bone resorption than clodronate.