Patients with end-stage renal disease (ESRD) who take calcium-based phosphate binders may take in high levels of elemental calcium that could lead to complications related to calcium balance, according to a new report.

Previous studies have demonstrated an association between use of calcium-based binders and hypercalcemia, vascular calcification, and adynamic bone disease. To examine the effects of calcium loading associated with calcium-based binders in ESRD patients, Rosamund J. Wilson, PhD, of Spica Consultants in Marlborough, UK, and J. Brian Copley, MD, of Shire Pharmaceuticals in Lexington, Massachusetts, conducted a post hoc analysis of data from a phase IV study of 752 ESRD patients who switched to lanthanum carbonate monotherapy for 16 weeks after having been on monotherapy with calcium acetate (551 patients) or calcium carbonate (201 patients).

Kidney Disease Outcomes Quality Initiative (KDOQI) 2003 guidelines recommend a maximum daily elemental calcium intake of 1.5 g/day and maximum total intake of calcium from all sources of 2 g/day, the investigators noted. The guidelines also suggest that calcium-based binders should be avoided in dialysis patients who have vascular calcification, hypercalcemia, or plasma parathyroid hormone (PTH) levels below 150 pg/mL. “Thus, the KDOQI guidelines emphasize the importance of minimizing calcium exposure while normalizing serum phosphate levels in patients with ESRD,” the authors stated.

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Of the 551 patients who were on calcium acetate prior to switching to lanthanum carbonate, 271 (49.3%) had an elemental calcium intake of at least 1.5 g/day at baseline, and 142 (25.8%) had an intake of at least 2.0 g/day, the maximum daily intake for all sources recommended by the KDOQI guidelines, the researchers reported in Drugs in Context (2017;6:212302). Mean serum phosphate levels were 6.1 mg/dL at baseline and 6.2 mg/dL after 16 weeks of lanthanum carbonate therapy. Their mean corrected serum calcium levels were 9.3 mg/dL and 9.2 mg/dL, respectively. Mean PTH levels were high at both time points (511.0 and 582.7 pg/mL, respectively.

Of the 221 patients on calcium carbonate before switching to lanthanum carbonate, 117 (58.2%) had an elemental calcium intake at baseline of at least 1.5 g/day, and 76 (37.8%) had an intake of at least 2.0 g/day, according to the investigators. Mean serum phosphate levels were 5.8 mg/dL at baseline and 5.8 mg/dL at 16 weeks. Their mean corrected calcium levels were comparable at baseline and 16 weeks (9.7 and 9.2 mg/dL, respectively), as were mean PTH levels (286.5 and 294 pg/mL, respectively), the researchers reported.

“This post hoc analysis of real-world clinical data shows that a large proportion of patients with ESRD taking calcium acetate/ calcium carbonate monotherapy to treat hyperphosphatemia ingest elemental calcium at levels above the KDOQI-recommended daily limits,” Dr Wilson and Dr Copley concluded. “These patients may be at risk of developing vascular calcification and adynamic bone disease. It is important to consider these findings when decisions are made regarding the comparative utility of calcium-based phosphate binders over non-calcium-based phosphate binders in patients with ESRD.”

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1. Wilson RJ, Copley JB. Elemental calcium intake associated with calcium acetate/carbonate in the treatment of hyperphosphatemia. Drugs Context 2017;6:212302.