BOSTON—Hidden hypercalcemia is common among new hemodialysis (HD) patients and it is associated with an increased mortality risk similar to that of apparent hypercalcemia, researchers reported at the National Kidney Foundation’s Spring Clinical Meetings.

Using data from a large dialysis organization (DaVita), Yoshitsugu Obi, MD, PhD, of the University of California Irvine School of Medicine, and collaborators studied 869 incident HD patients with measured serum ionized calcium, total calcium, albumin, phosphorus, intact parathyroid hormone, and bicarbonate from October 2007 to December 2011.

Among patients with high ionized calcium (levels above 1.32 mmol/L), 88% and 70% were incorrectly categorized as being normocalcemic using uncorrected and corrected total calcium, respectively, according Dr. Obi’s group. The researchers considered these patients to have hidden hypercalcemia.

Compared with patients who had low-normal ionized calcium (1.16–1.24 mmol/L), patients with high ionized calcium had a significant 75% increased mortality risk in adjusted analyses. Compared with patients who had normocalcemia (ionized calcium level 1.16–1.32 mmol/L), those with hidden hypercalcemia on the basis of uncorrected and corrected total calcium had a significant 71% and 75% increased mortality risk, respectively, in adjusted analyses.