In Reply to ‘Dialysate Calcium Concentration and Mineral Metabolism in Long and Long-Frequent Hemodialysis’

Abstract

Basile et al1Basile C. Lisi P. Lomonte C. Dialysate calcium concentration and mineral metabolism in long and long-frequent hemodialysis.Am J Kidney Dis. 2013; 62: 1018-1019Abstract Full Text Full Text PDF PubMed Scopus (2) Google Scholar have raised concerns about our recommendation for a dialysate calcium concentration ≥ 1.5 mmol/L for most patients treated with long or long-frequent hemodialysis. The authors cite the results of their study, in which patients treated with a 1.5-mmol/L dialysate calcium concentration for 8 hours on the GENIUS system (Fresenius Medical Care, Germany) gained an average of 298 mg of calcium.2Zimmerman D.L. Nesrallah G.E. Chan C.T. et al.Dialysate calcium concentration and mineral metabolism in long and long-frequent hemodialysis: a systematic review and meta-analysis for a Canadian Society of Nephrology clinical practice guideline.Am J Kidney Dis. 2013; 62: 97-111Abstract Full Text Full Text PDF PubMed Scopus (16) Google Scholar, 3Basile C. Libutti P. Di Turo A.L. et al.Calcium mass balances during standard bicarbonate dialysis and long-hour slow-flow bicarbonate hemodialysis.J Nephrol. 2011; 24: 742-748Crossref PubMed Scopus (7) Google Scholar This is contrary to the study by Al-Hejaili et al,4Al-Hejaili F. Kortas C. Leitch R. Nocturnal but not short hours quotidian hemodialysis requires an elevated dialysate calcium concentration.J Am Soc Nephrol. 2003; 14: 2322-2328Crossref PubMed Scopus (104) Google Scholar in which patients enrolled in the daily/nocturnal hemodialysis study lost an average of 172 mg of calcium during a 6-hour dialysis session. Furthermore, with a 1.25-mmol/L dialysate calcium concentration, patients lost 2 mmol of calcium per hour, which would result in a 4-g calcium loss with 8 hours of treatment 6 nights per week.4Al-Hejaili F. Kortas C. Leitch R. Nocturnal but not short hours quotidian hemodialysis requires an elevated dialysate calcium concentration.J Am Soc Nephrol. 2003; 14: 2322-2328Crossref PubMed Scopus (104) Google Scholar The results of the 2 studies are not directly comparable: blood pump speeds, dialysate flows, patient populations, and serum calcium values were all different. Importantly, calcium balance is affected by more than dialysate calcium concentration. It includes dietary and phosphate binder intake, as well as the gastrointestinal, urinary, and other losses that must be taken into consideration. The current KDOQI (Kidney Disease Outcomes Quality Initiative) recommendation for calcium intake for patients with end-stage renal disease is intended to mirror the recommendations for the general population of 1,500-2,000 mg/d.5National Kidney FoundationKDOQI guidelines for bone metabolism and disease in chronic kidney disease.http://www.kidney.org/professionals/kdoqi/guidelines_bone/Guide5.cfmGoogle Scholar Many patients treated with long and long-frequent hemodialysis will no longer require phosphate binders; dietary calcium becomes their major but inadequate source of calcium intake. This is evidenced by an increasing serum parathyroid hormone level and decreasing bone mineral density.2Zimmerman D.L. Nesrallah G.E. Chan C.T. et al.Dialysate calcium concentration and mineral metabolism in long and long-frequent hemodialysis: a systematic review and meta-analysis for a Canadian Society of Nephrology clinical practice guideline.Am J Kidney Dis. 2013; 62: 97-111Abstract Full Text Full Text PDF PubMed Scopus (16) Google Scholar, 6Toussaint N.D. Review: differences in prescription between conventional and alternative haemodialysis.Nephrology. 2010; 15: 399-405Crossref PubMed Scopus (7) Google Scholar For this reason, we have recommended a dialysate calcium concentration ≥ 1.5 mmol/L, with adjustments to be made based on serum calcium and parathyroid hormone levels. Dialysate Calcium Concentration and Mineral Metabolism in Long and Long-Frequent HemodialysisAmerican Journal of Kidney DiseasesVol. 62Issue 5PreviewZimmerman et al1 concluded in their systematic review and meta-analysis that for most patients treated with long and long-frequent hemodialysis (HD), a dialysate calcium concentration ≥ 1.5 mmol/L prevents both an increase in parathyroid hormone (PTH) levels and a decline in bone mineral density without increased risk of calcification. These conclusions are drawn without discussion of the critical role that dialysate calcium mass balance plays in the mineral metabolism of dialysis patients. Very few published studies have measured dialysate calcium mass balance by direct dialysate quantification in intensive HD. Full-Text PDF