How to manage hyperphosphatemia?

Management of Hyperphosphatemia with Inorganic Phosphorus Level of 5.18 mg/dL

For patients with hyperphosphatemia (phosphorus level 5.18 mg/dL), treatment should focus on dietary phosphate restriction, particularly limiting inorganic phosphate sources from processed foods, along with phosphate binders only if hyperphosphatemia is persistent or progressive. 1

Underlying Principles

The 2017 KDIGO Chronic Kidney Disease-Mineral and Bone Disorder (CKD-MBD) guidelines have updated their approach to hyperphosphatemia management, abandoning the previous recommendation to maintain phosphate in the normal range for all CKD patients. Instead, treatment should specifically target patients with established hyperphosphatemia 1.

Dietary Management - First Line Approach

1. Focus on phosphate bioavailability:

   • Limit inorganic phosphate sources (food additives) which have 80-100% absorption
   • Animal-based phosphate is moderately absorbable (40-60%)
   • Plant-based phosphate has lower absorption (20-50%) due to phytates 1

2. Practical dietary recommendations:

   • Guide patients toward fresh and homemade foods rather than processed foods
   • Educate about reading food labels for phosphate additives
   • Avoid excessive dietary phosphate restriction that might compromise protein intake 1
   • Consult with an experienced dietitian who can help balance phosphate restriction with adequate nutrition 1

Pharmacological Management - For Persistent Hyperphosphatemia

If dietary measures are insufficient and hyperphosphatemia is persistent or progressive, phosphate binders should be considered:

1. Calcium-based binders:

   • Calcium acetate or calcium carbonate
   • Limit to <1g of elemental calcium daily to avoid hypercalcemia and vascular calcification 2
   • Monitor for hypercalcemia, vascular calcification, and adynamic bone disease

2. Non-calcium-based binders:

   • Sevelamer hydrochloride/carbonate: FDA-approved for controlling serum phosphorus in CKD patients on dialysis 3

     • Starting dose: 800 mg (one tablet) three times per day with meals
     • Adjust by one tablet per meal in two-week intervals to reach target phosphorus level
     • Monitor for gastrointestinal side effects (dyspepsia, diarrhea, constipation)
     • Note drug interactions: separate administration from ciprofloxacin and mycophenolate mofetil 3

   • Lanthanum carbonate: Effective alternative with biliary excretion

   • Magnesium-based binders: Consider in patients without hypermagnesemia

Monitoring and Follow-up

1. Monitor serum phosphorus, calcium, and PTH levels regularly
2. Adjust phosphate binder dose based on serum phosphorus levels
3. Assess for compliance with diet and medication
4. Watch for signs of hypercalcemia if using calcium-based binders

Special Considerations

1. High PTH levels: Hyperphosphatemia may be worsened by secondary hyperparathyroidism, requiring management of both conditions 4

2. Protein intake: Balance phosphate restriction with adequate protein intake, as higher protein intake is associated with higher phosphorus levels 4

3. Dialysis patients: Ensure efficient dialysis removal of phosphate in addition to dietary and pharmacological interventions 5

Pitfalls to Avoid

1. Overrestricting dietary protein: This can lead to malnutrition without adequately controlling phosphate

2. Relying solely on phosphate binders: Dietary modification is essential and should be implemented first

3. Ignoring food additives: Processed foods with phosphate additives can increase phosphorus intake up to 2-fold compared to unprocessed foods 1

4. Excessive calcium load: High doses of calcium-based binders may contribute to vascular calcification

The management of hyperphosphatemia requires a balanced approach focusing first on dietary modifications targeting inorganic phosphate sources, followed by phosphate binders if hyperphosphatemia persists, with careful consideration of the risks and benefits of different binder types.