How to manage hyperphosphatemia in a patient undergoing dialysis (renal replacement therapy)?

From the Guidelines

To control high phosphorus levels while on dialysis, it is essential to limit dietary phosphate intake and consider phosphate-lowering therapies, such as phosphate binders, only in the event of progressive or persistent hyperphosphatemia. The most recent and highest quality study, 1, suggests that phosphate-lowering treatments may only be indicated in the event of progressive or persistent hyperphosphatemia and not for prevention.

Key Recommendations

• Limit dietary phosphate intake, as suggested by 1, which recommends limiting dietary phosphate intake in the treatment of hyperphosphatemia alone or in combination with other treatments.
• Consider phosphate source, such as animal, vegetable, or additives, when making dietary recommendations, as mentioned in 1.
• Take phosphorus binders, such as calcium acetate, sevelamer, lanthanum carbonate, or ferric citrate, with meals and snacks as prescribed by your doctor, as these medications work by binding to phosphorus in food, preventing its absorption into the bloodstream.
• Attend all scheduled dialysis sessions, as dialysis helps remove excess phosphorus from your blood, and regular blood tests will monitor your phosphorus levels, allowing your healthcare team to adjust your treatment plan as needed.

Important Considerations

• High phosphorus levels occur in dialysis patients because damaged kidneys cannot effectively remove phosphorus from the blood, which can lead to bone disease, itching, and cardiovascular complications if left uncontrolled.
• The current evidence suggests that excess exposure to calcium may be harmful across all GFR categories of CKD, as mentioned in 1.
• Phosphate-lowering treatment decisions should be individualized, and there is no explicit recommendation about a maximum dose of calcium-based binders, as stated in 1.

Additional Guidance

• Restrict foods high in phosphorus, such as dairy products, processed foods, nuts, whole grains, and dark sodas, and instead choose lower phosphorus options like rice milk, fresh fruits, vegetables, and white bread.
• Consider the potential harm of liberal calcium exposure in normophosphatemic adults with CKD stage G3b or G4, as suggested by 1.

From the FDA Drug Label

The ability of sevelamer hydrochloride to lower serum phosphorus in CKD patients on dialysis was demonstrated in six clinical trials: one double-blind placebo-controlled 2-week study (sevelamer hydrochloride N=24); two open-label uncontrolled 8-week studies (sevelamer hydrochloride N=220) and three active-controlled open-label studies with treatment durations of 8 to 52 weeks (sevelamer hydrochloride N=256).

Eighty-four CKD patients on hemodialysis who were hyperphosphatemic (serum phosphorus >6 mg/dL) following a two-week phosphate binder washout period received sevelamer hydrochloride and active-control for eight weeks each in random order.

Both treatments significantly decreased mean serum phosphorus by about 2 mg/dL (Table 5).

To control high phosphorus levels in someone on dialysis, sevelamer hydrochloride can be used. The medication has been shown to decrease mean serum phosphorus levels by about 2 mg/dL in clinical trials 2.

• The average daily dose of sevelamer hydrochloride used in the studies was between 4.9 g and 6.5 g.
• The dose of sevelamer hydrochloride can be titrated up to control serum phosphorus levels.
• It is essential to monitor serum phosphorus levels regularly to adjust the dose as needed.

From the Research

Controlling High Phosphorous in Dialysis Patients

To control high phosphorous levels in dialysis patients, several strategies can be employed:

• Dietary Phosphate Control: Limiting dietary phosphate intake is crucial, as dialytic removal does not equal the high phosphate intake linked to the high dietary protein requirement of dialysis patients 3.
• Phosphate Binders: The use of intestinal phosphate binders is mandatory to reduce phosphate net intestinal absorption, although their efficacy is limited in the case of an uncontrolled dietary phosphate load 3.
• Dialysis Techniques: Using mixed diffusive-convective hemodialysis techniques and increasing the number and/or duration of dialysis sessions can enhance phosphorus mass removal through dialysis 3.
• New Therapies: Recent advances in phosphate absorption pathways have led to the development of new non-binder therapies that block phosphate absorption, which may provide an opportunity to rethink phosphate management 4.

Dietary Recommendations

Patients on dialysis should:

• Avoid foods that are naturally rich in phosphate and processed foods with phosphate-containing preservatives 3.
• Choose foods with a low phosphate-to-protein ratio, such as egg white or protein from a vegetable source 3.
• Prefer boiling as a cooking procedure, as it induces food demineralization, including phosphate loss 3.

Phosphate Binder Options

Studies have compared the effectiveness of different phosphate binders, including:

• Sevelamer Hydrochloride: Compared to calcium carbonate, sevelamer hydrochloride has been shown to have a similar effect on controlling plasma calcium, phosphate, and parathyroid hormone levels 5.
• Calcium Acetate: Calcium acetate has been found to be more effective than sevelamer hydrochloride in controlling serum phosphorus and calcium-phosphate product 6.