A Modified Method for Reducing Renal Injury in Zoledronic Acid Treatment of Hypercalcemia and Adverse Skeletal Events

AIMS: In this paper, we have reported a previously undescribed risk factor of deterioration of renal function in zoledronic acid treatment of skeletal metastasis – high serum calcium level. Based on this consideration, a modified method of treatment of hypercalcemia (HCM) with zoledronic acid is suggested in this paper. MATERIAL AND METHODS: Bone scan findings of 1090 cancer patients were analyzed, of which 26 had intense renal parenchymal uptake as a result of HCM or bone metastases. Subsequently, a total of 56 bone metastases patients with zoledronic acid treatment were divided into three groups: HCM group who were pre-treated to normal serum calcium level (13 patients), HCM group (19 patients), and normal serum calcium group (24 patients). RESULTS: More patients with intense renal parenchymal uptake were hyperglycemic, statistically significantly (18/26 versus 19/1064, P = 2.1, E-78). No more patients with intense renal parenchymal uptake were associated with bone metastases (14/26 versus 438/1064, P = 0.20). Subsequently, more HCM patients receiving zoledronic acid treatment showed renal injury compared to patients with normal serum calcium level (5/15 versus 2/24, P < 0.05) and HCM patients with pre-treatment to normal serum calcium level (5/15 versus 1/17, P < 0.05). CONCLUSIONS: Intense renal parenchymal uptake of bisphosphonates is closely related to HCM rather than to bone metastases in cancer patients. The serum calcium should be measured and reduced to normal level before zoledronic acid is used in managements of adverse skeletal events in order to decrease the risk of renal injury.