Confusion on the Complexity of Calcium Balance
Article first published online: 29 OCT 2010
© 2010 Wiley Periodicals, Inc.
Seminars in Dialysis
Volume 23, Issue 5, pages 492–497, September/October 2010
How to Cite
Moe, S. M. (2010), Confusion on the Complexity of Calcium Balance. Seminars in Dialysis, 23: 492–497. doi: 10.1111/j.1525-139X.2010.00771.x
- Issue published online: 29 OCT 2010
- Article first published online: 29 OCT 2010
Calcium balance is an overall assessment of the net calcium taken in minus the net calcium taken out. It can only be assessed when patients are in steady state and requires complicated isotope methods that can simultaneously assess intestinal absorption and endogenous secretion, urinary and stool excretion, bone calcium uptake and removal, and dialysate calcium removal. By virtue of the need for steady state, formal balance studies cannot be accurately carried out in patients on dialysis. However, many of the components of calcium balance have been assessed. Importantly, because 99% of calcium is in bone, studies must accurately assess both the rapidly exchangeable calcium from the bone surface and the net bone calcium balance that results from the difference in bone formation minus resorption. While it is tempting to adjust the dialysate calcium concentration to correct the net positive calcium balance that is likely present in patients who receive calcium-based phosphate binders, the reality is that the highly variable, yet important, role of bone cannot be easily assessed at the bedside. Thus, it is best to prevent the calcium overload in the first place by avoiding high-dose calcium-based phosphate binders and optimizing bone remodeling.