The calcium–phosphorus in guidelines for CKD-MBD

To the Editor: O'Neill1.O'Neill W.C. The fallacy of the calcium–phosphorus product.Kidney Int. 2007; 72: 792-796Abstract Full Text Full Text PDF PubMed Scopus (111) Google Scholar revealed the fact that the calcium–phosphorus product (Ca × P) is an independent risk factor for mortality and morbidity is also questionable in his review. Although the Kidney Disease Outcomes Quality Initiative (KDOQI) guideline states that the Ca × P should be maintained below 55 mg2 per 100 ml2,2.National Kidney Foundation K/DOQI Clinical Practice Guidelines for bone metabolism and disease in chronic kidney disease.Am J Kidney Dis. 2003; 42: S1-S201PubMed Google Scholar considering the Ca × P as well as serum Ca and P make the algorithms in the KDOQI guideline complicated. As O'Neill indicated, in the largest cross-sectional study, both serum Ca and serum P were strongly associated with coronary calcification but Ca × P was not analyzed.3.Raggi P. Boulay A. Chasan-Taber S. et al.Cardiac calcification in adult hemodialysis patients.J Am Coll Cardiol. 2002; 39: 695-701Abstract Full Text Full Text PDF PubMed Scopus (951) Google Scholar We examined the relationship of Ca × P and serum Ca or serum P in 1395 patients with hemodialysis. We did not find any correlation between Ca × P and serum Ca. Conversely, we found strong significant correlation between Ca × P and serum P (R=0.95, P<0.001, Figure 1). Because the serum Ca × serum P can usually be kept in an appropriate level by maintaining serum P and corrected serum Ca within the target range, Japanese guidelines for the treatment of secondary hyperparathyroidism in patients on dialysis did not adopt Ca × P for an index. Accordingly, Japanese guidelines consist of nine blocks that depend on serum Ca levels and serum P levels (high, suitable, low; 3 × 3) and indicate recommended treatments in each block (Figure 2). Without adopting Ca × P for an index make guidelines simple, resulting in high feasibility. We should reconsider the value of Ca × P in guidelines for Chronic kidney disease-Mineral and Bone Disorder (CKD-MBD).Figure 2The management of serum P and Ca levels (Japanese guidelines for the treatment of secondary hyperparathyroidism in patients on dialysis).View Large Image Figure ViewerDownload (PPT)