What is the best treatment for hyperphosphatemia?

Management of Hyperphosphatemia

For hyperphosphatemia treatment, a combination of dietary phosphate restriction, non-calcium phosphate binders for persistent elevations, and addressing underlying causes is recommended, with calcium-based binders used cautiously due to calcification risks. 1

Assessment and Monitoring

• Monitor serum phosphate, calcium, and PTH levels together as these parameters interact 2, 1
• Frequency of monitoring depends on CKD stage:
  • CKD G3a-G3b: every 6-12 months
  • CKD G4: every 3-6 months
  • CKD G5/G5D: every 1-3 months 1
• Target phosphate levels:
  • CKD Stages 3-4: 2.7-4.6 mg/dL
  • CKD Stage 5/Dialysis: 3.5-5.5 mg/dL 1
• Assess for vascular calcification using lateral abdominal radiograph or echocardiogram 1

First-Line Treatment: Dietary Management

• Restrict dietary phosphate to 800-1,000 mg/day when serum phosphorus is elevated (>4.6 mg/dL in CKD stages 3-4 or >5.5 mg/dL in CKD stage 5) 1
• Consider phosphate bioavailability from different sources:
  • Animal-based phosphate: 40-60% absorption
  • Plant-based phosphate: 20-50% absorption
  • Inorganic phosphate (food additives): highest bioavailability 1
• Guide patients toward fresh and homemade foods rather than processed foods to avoid phosphate additives 2
• Involve an experienced dietitian in phosphorus management 1

Second-Line Treatment: Phosphate Binders

• Initiate phosphate binders only for progressively or persistently elevated serum phosphate levels 2
• Non-calcium-based binders are preferred, particularly in patients with:
  • Normal or elevated calcium levels
  • Arterial calcification
  • Adynamic bone disease
  • Persistently low PTH levels 1

Types of Phosphate Binders:

1. Non-calcium-based binders (preferred option):

   • Sevelamer: No systemic accumulation, may have beneficial effects on cardiovascular disease 3
   • Lanthanum carbonate: Effective but has biliary excretion 3
   • Magnesium salts: Effective but has urinary excretion 3

2. Calcium-based binders (use with caution):

   • Calcium acetate: Effective but may lead to hypercalcemia and vascular calcification 4
   • Calcium carbonate: Similar concerns as calcium acetate 2
   • Limit total elemental calcium from all calcium-based binders to 1,500-2,000 mg/day 1
   • Initial dose of calcium acetate: 2 tablets (667 mg each) per meal, adjusting as needed 4

3. Avoid aluminum-containing phosphate binders for long-term use due to toxicity risk 1

Additional Strategies for Refractory Hyperphosphatemia

• For dialysis patients: Increase dialytic phosphate removal 1
• Maintain dialysate calcium concentration between 1.25-1.50 mmol/L (2.5-3.0 mEq/L) 1
• Consider more frequent dialysis for persistent hyperphosphatemia >7.0 mg/dL 1
• Evaluate and treat secondary hyperparathyroidism, as elevated PTH contributes to hyperphosphatemia 5
• Consider vitamin D supplementation and calcimimetics (e.g., cinacalcet) for severe hyperparathyroidism 1

Common Pitfalls to Avoid

• Focusing solely on phosphate without considering calcium and PTH levels 2
• Using calcium-based binders in patients with hypercalcemia or vascular calcification 2, 1
• Excessive dietary protein restriction may lead to malnutrition; focus on phosphate sources with lower bioavailability 2
• Failing to educate patients about hidden phosphate sources in food additives 1
• Prescribing phosphate binders for normophosphatemic patients, which may not be beneficial and could be harmful 2
• Exceeding 2,000 mg/day total calcium intake from diet and phosphate binders 1

Early intervention with dietary phosphate restriction in early CKD stages may help preserve renal function and prevent elevation of FGF-23 levels 6, addressing hyperphosphatemia before it contributes to further kidney damage and cardiovascular complications.