Most patients are unable to consistently achieve target phosphorus levels1,2
Dr. Glenn Chertow
Watch Dr. Glenn Chertow explain how we may be underestimating the magnitude of the problem.

A recent patient chart audit found that evaluating the proportion of patients above target phosphorus level in a single month may underestimate the magnitude of the problem1,2

In any given month,
42%
of patients are unable to achieve target phosphorus levels
Over a 6-month period,
77%
of patients are unable to maintain target phosphorus levels

Demonstrated in a 2019 chart audit including the records of 1,015 patients on dialysis and on phosphorus-lowering therapy, submitted by 159 nephrologists.

Target phosphorus levels were defined as ≤5.5 mg/dL.1

Evaluating the proportion of patients above target in a single month may underestimate the magnitude of the problem.

Both elevated phosphorus and time spent with elevated phosphorus increase the risk of cardiovascular mortality3-6

mortality risk graph serum phosphorus level mortality risk graph serum phosphorus level

Likelihood of death for patients on dialysis was significantly increased when serum phosphorus levels were only 0.5 mg/dL to 1 mg/dL over the reference range of 4.0 mg/dL to 5.0 mg/dL.3

cardiovascular hospitalization graph serum phosphorus level mortality risk graph serum phosphorus level

Area under the curve (AUC) takes into account both the serum phosphorus concentration and the amount of time a patient’s serum phosphorus concentration was above the target range. Patients with higher AUC values had worse phosphorus control; for example, a patient maintaining a serum phosphorus level of exactly 5.5 mg/dL or 6.5 mg/dL over 6 months would have an AUC of 1 or 2, respectively.6

Lopes MB, Karaboyas A, Bieber B, et al. Impact of longer term phosphorus control on cardiovascular mortality in hemodialysis patients using an area under the curve approach: results from the DOPPS. Nephrol Dial Transplant. 2020;35(10):1794-1801. doi: 10.1093/ndt/gfaa054. Adapted and reproduced by permission of Oxford University Press on behalf of the ERA-EDTA.

Dr. Geoffrey Block
Watch Dr. Geoffrey Block explain the cardiovascular consequences of hyperphosphatemia.
Dr. Block currently serves as a member of the Board of Directors at Ardelyx, Inc.

Clinical practice guidelines for lowering elevated phosphate levels

KDOQI logo
In patients with CKD stage 5 and those treated with dialysis, the KDOQI guidelines (2003) recommend that serum levels of phosphorus should be maintained between 3.5 mg/dL–5.5 mg/dL7
Produced by the National Kidney Foundation, Inc.
All rights reserved.
kdigo logo
In patients with CKD G3a–G5D, the KDIGO guidelines (2017) recommend lowering elevated phosphate levels toward the normal range (2.5 mg/dL–4.5 mg/dL)8,9
Patients and healthcare providers discuss challenges managing phosphorus

What are the difficulties from the healthcare team’s perspective?

It’s important to point out that our inability to consistently achieve target phosphorus levels is not anybody’s fault. Patients are not to blame. Healthcare providers are not to blame. Look, I think we are all trying our best and that we have done the best we can with the tools that we have currently available to us.
But because of the limitations of these current strategies, controlling hyperphosphatemia remains challenging. We must revisit our current approach so that we can do better at managing this condition that is associated with significant cardiovascular risk to our patients.
– Dr. Steven Fishbane
Chief of Nephrology
Northwell Health
Dr. Steven Fishbane
Watch Dr. Steven Fishbane discuss the challenges we face in the management of hyperphosphatemia.
Dawn
Dawn shares her experience of managing phosphorus as a patient with CKD on dialysis.

How do patients feel about managing their phosphorus?

Living with kidney disease has been a series of challenges. Phosphorus management has got to be one of the most challenging aspects of kidney disease, it has been an uphill battle. I have had kidney disease for 30 years and it’s still an uphill battle.
– Dawn, a patient living with kidney disease for 30 years

Looking deeper into the science of phosphate absorption has revealed the primacy of the paracellular pathway

Our knowledge around phosphate absorption has evolved
As the science of intestinal phosphate absorption advances, it is becoming more evident that the paracellular pathway is the primary mechanism by which phosphate absorption occurs in humans. This new mechanistic understanding has important implications for the management of hyperphosphatemia.
– Dr. Stuart Sprague
Chief, Division of Nephrology and Hypertension
Northshore University HealthSystem
Dr. Stuart Sprague
Watch Dr. Stuart Sprague describe our new mechanistic understanding of phosphate absorption.

We now know that the paracellular pathway is the primary pathway by which phosphate absorption occurs10-12

Dietary phosphate absorption occurs via 2 distinct intestinal pathways10,11
  • 1
    Paracellular absorption occurs passively along concentration gradients through tight junction complexes between cell membranes.10,11
    • The paracellular pathway is responsible for the bulk of phosphate absorption and does not appear to saturate12-14
  • 2
    Transcellular absorption occurs via active transport through cell membranes and is less relevant as a mechanism of phosphate absorption in humans.10,11
Mechanisms of Phosphate Absorption
mechanism of phosphate absorption
Watch a video of the
paracellular pathway in action
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      Ardelyx is committed to advancing the treatment of hyperphosphatemia in patients with CKD on dialysis