Hemodialysis (HD) patients reap a survival benefit when serum phosphate levels are reduced toward a safer target range of 3.6 to 5.2 mg/day, according to new findings reported at the European Renal Association-European Dialysis and Transplant Association 2017 Congress in Madrid.

The findings are from an analysis of data from COSMOS (Current management of secondary hyperparathyroidism: A multicentre observational study).

A 1.1 mg/dL reduction in serum phosphate from an average 6.5 mg/dL toward that safer target range was associated with a 12% lower risk of mortality, COSMOS investigators Jorge Cannata-Andia, MD, PhD, and Jose Luis Fernández, PhD, reported. Previous COSMOS results suggested 3.6 to 5.2 mg/dL as the serum phosphate range with the lowest mortality risk over 3 years of follow-up. For the latest analysis, the team examined COSMOS data from 6797 HD patients randomly chosen from 227 centers in 20 European countries.

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“For the first time, using a COSMOS analyses which mimics as much as possible what happens in randomized clinical trials, it was found that the reduction of serum phosphorus in dialysis patients may render the expected benefits, as it is associated to better survival,” Drs Cannata-Andia and Fernández stated in a news release.

Importantly, the timing of blood withdrawal influenced serum phosphate values. Serum phosphate levels were significantly higher after a longer interdialytic interval of 3 days (i.e., after the weekend).

Clinicians need to be aware of this difference in order to adjust phosphate-lowering therapy appropriately for individual patients with hyperphosphatemia. Given its important clinical implications, the investigators suggested that future guidelines weigh the influence of the interdialytic period on phosphate values.

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