How to manage hypercalcemia and hyperphosphatemia in the context of an infection?

Management of Hypercalcemia and Hyperphosphatemia in Infection

Aggressive hydration with intravenous fluids is the first-line treatment for both hypercalcemia and hyperphosphatemia in the context of infection, followed by specific treatments based on severity.

Initial Assessment and Management

Hydration

• Begin with aggressive IV hydration using normal saline (0.9% NaCl) to:
  • Promote renal calcium and phosphate excretion
  • Correct dehydration that commonly accompanies infection
  • Maintain urine output at minimum 100 mL/hour (3 mL/kg/hour in children <10 kg) 1

Addressing Infection

• Prompt identification and treatment of the underlying infection is essential
• Infections must be strictly controlled to prevent deterioration of any metabolic abnormalities 1

Management of Hypercalcemia

Mild Hypercalcemia (Ca <12 mg/dL)

• Continue IV hydration
• Consider loop diuretics (furosemide) after adequate hydration to enhance calcium excretion
• Monitor serum calcium levels every 6-12 hours

Moderate to Severe Hypercalcemia (Ca >12 mg/dL)

1. Bisphosphonates: Zoledronic acid is preferred for treatment of hypercalcemia 1

   • Dosage: 4 mg IV infused over 15 minutes (never over 5 minutes due to increased risk of renal toxicity) 2
   • Contraindicated in severe renal impairment

2. Calcitonin: For rapid but short-term calcium reduction

   • Can be used while waiting for bisphosphonates to take effect
   • 4-8 IU/kg subcutaneously or intramuscularly every 12 hours

3. Glucocorticoids: Particularly effective when hypercalcemia is due to:

   • Granulomatous disorders
   • Certain lymphomas
   • Vitamin D excess 3

Life-threatening Hypercalcemia

• Consider hemodialysis, especially in patients with renal failure or when other treatments fail 1
• Calcium-free dialysate should be used

Management of Hyperphosphatemia

Mild Hyperphosphatemia (<1.62 mmol/L)

• IV hydration to enhance phosphate excretion
• Eliminate phosphate from IV solutions 1
• Consider oral phosphate binders:
  • Aluminum hydroxide: 50-100 mg/kg/day divided in 4 doses (limit to 1-2 days to avoid aluminum toxicity) 1

Moderate to Severe Hyperphosphatemia

1. Phosphate binders:

   • Non-calcium based binders (sevelamer) preferred if patient also has hypercalcemia
   • Calcium acetate if calcium levels are normal or low:
     • Initial dose: 2 capsules (667 mg each) with each meal
     • Increase gradually to 3-4 capsules per meal as needed 4

2. Maintain calcium-phosphorus product below 55 mg²/dL² to reduce risk of tissue calcification 4

3. Hemodialysis: Consider for severe, refractory hyperphosphatemia, especially with renal dysfunction 1

   • Hemodialysis is more effective than continuous venovenous hemofiltration or peritoneal dialysis for phosphate clearance

Special Considerations

Monitoring

• Check serum calcium and phosphate levels every 6-12 hours until stable
• Monitor renal function closely
• For patients receiving calcium-based phosphate binders, monitor for hypercalcemia
• Watch for signs of calcium-phosphate precipitation in tissues

Cautions

• Avoid calcium-containing IV fluids in hypercalcemia
• Do not use calcium-based phosphate binders in patients with hypercalcemia 5
• Avoid aluminum-based phosphate binders for extended periods due to risk of aluminum toxicity 5
• When using zoledronic acid, ensure adequate hydration but avoid volume overload 2

Pitfalls to Avoid

1. Failing to treat the underlying infection
2. Using calcium-containing solutions in hypercalcemia
3. Administering bisphosphonates too rapidly (increased risk of renal toxicity)
4. Overlooking the need for more frequent monitoring in severe cases
5. Delaying dialysis when indicated in severe, refractory cases

By following this approach, both hypercalcemia and hyperphosphatemia can be effectively managed while treating the underlying infection, reducing the risk of complications and improving patient outcomes.