Phosphate metabolism in chronic kidney disease: from pathophysiology to clinical management

Hyperphosphatemia is considered as an independent risk factor for surrogate clinical endpoints like vascular calcification (VC) and bone disease, or hard clinical outcomes like cardiovascular events. To date, various treatment options for phosphate removal or reduction are available. The great expectations put into calcium-based phosphate binders were mitigated because of their possible contribution to progressive VC, particularly in patients treated simultaneously with active vitamin D derivatives. Thus, a paradigm change occurred whereby the main clinical concern shifted from the avoidance of hypocalcemia to that of the consequences of inducting a positive calcium balance. Sevelamer-HCl treatment allowed a comparable control of hyperphosphatemia with a lower risk of hypercalcemia than calcium-based phosphate binders, and a slower progression of VC; however, convincing evidence of improved clinical outcomes in dialysis patients is lacking. Although data on the safety and efficacy of lanthanum carbonate in the treatment of hyperphosphatemia have been provided in long-term clinical studies, there is still an ongoing scientific debate about its possible long-term toxicity. Moreover, there are no data from randomized clinical trials demonstrating beneficial effects of La carbonate treatment on VC or cardiovascular outcomes. In the absence of convincing clinical trials testing the effects of non-metal-based phosphate binders on cardiovascular and global outcomes it appears reasonable to maintain bone health and mineral homeostasis by mainly relying on adaptations of standard therapies. Noncalcium, non-aluminum-based binders might be reserved for patients with major mineral metabolism abnormalities and a high risk of VC.