Risk factors for symptomatic hypocalcaemia complicating treatment with zoledronic acid
Article first published online: 17 FEB 2008
© 2008 The Authors Journal compilation © 2008 Royal Australasian College of Physicians
Internal Medicine Journal
Volume 38, Issue 8, pages 635–637, August 2008
How to Cite
Chennuru, S., Koduri, J. and Baumann, M. A. (2008), Risk factors for symptomatic hypocalcaemia complicating treatment with zoledronic acid. Internal Medicine Journal, 38: 635–637. doi: 10.1111/j.1445-5994.2007.01580.x
Potential conflicts of interest: None
- Issue published online: 3 SEP 2008
- Article first published online: 17 FEB 2008
- Received 25 June 2007; accepted 1 October 2007
- zoledronic acid;
- multiple myeloma
Background: The bisphosphonate zoledronic acid is commonly prescribed to prevent skeletal complications in patients with multiple myeloma or metastatic cancer. Although symptomatic hypocalcaemia is a potential risk of treatment, it has been thought to be uncommon.
Aims: After seeing several episodes of symptomatic hypocalcaemia following zoledronic acid administration, we undertook a review to determine the incidence of this complication in our population and to attempt to identify risk factors.
Methods: We reviewed the records of all patients receiving zoledronic acid in two teaching hospitals over a 2-year period. Findings collected included the indication for treatment, whether dosing was adjusted for creatinine clearance, coadministered medications, serum chemistries and clinical course.
Results: Of 120 patients who received a total of 546 zoledronic acid infusions, hypocalcaemia developed related to 55 infusions (10%) in 42 patients (35%). Symptomatic hypocalcaemia requiring i.v. supplementation occurred in 10 patients (8%), in spite of appropriate dose adjustment for creatinine clearance and despite prophylactic administration of oral calcium and vitamin D. More patients who became hypocalcaemic developed impairment of creatinine clearance during zoledronic acid treatment than in the group that remained normocalcaemic. Hypomagnesaemia was found in all patients who developed hypocalcaemia who had serum magnesium measured.
Conclusions: Hypocalcaemia was common in our patient group following zoledronic acid treatment. Because of the prolonged elimination half-life of this agent (146 h), renal impairment occurring during a number of days after administration may increase risk. Hypomagnesaemia may further increase risk by blunting compensatory increase in parathyroid hormone secretion.