Can Tums (calcium carbonate) be used to lower phosphate levels?

Use of Calcium Carbonate (Tums) for Lowering Phosphate Levels

Yes, Tums (calcium carbonate) can be effectively used as a phosphate binder to lower serum phosphate levels in patients with hyperphosphatemia, particularly in those with chronic kidney disease (CKD). 1

Mechanism of Action and Efficacy

Calcium carbonate works by binding to dietary phosphate in the gastrointestinal tract, forming insoluble calcium phosphate complexes that are excreted in feces, thus preventing phosphate absorption. This mechanism makes it an effective phosphate binder in the management of hyperphosphatemia.

Key points about calcium carbonate's efficacy:

• Calcium carbonate has been shown to effectively lower serum phosphorus concentrations in patients with CKD 1
• It can be used in both adult and pediatric populations with hyperphosphatemia 1
• Studies have demonstrated that calcium carbonate can control phosphate levels as effectively as other phosphate binders 2, 3

Clinical Considerations

When to Use Calcium Carbonate

• In patients with CKD stages G3a to G5D who have progressively or persistently elevated serum phosphate 1
• In patients with hyperphosphatemia associated with tumor lysis syndrome 1
• In patients with normal or low serum calcium levels 1

Dosing

• Typical dosing is with meals to maximize phosphate binding
• Dosage should be adjusted based on serum phosphate and calcium levels
• For tumor lysis syndrome, calcium carbonate can be administered orally or nasogastrically 1

Limitations and Cautions

Several important limitations must be considered when using calcium carbonate:

1. Risk of hypercalcemia: Calcium carbonate provides elemental calcium that can be absorbed, potentially leading to hypercalcemia 1, 4, 2

2. Vascular calcification risk: The 2017 KDIGO guidelines suggest restricting the dose of calcium-based phosphate binders in adult patients with CKD due to concerns about vascular calcification 1

3. Contraindications:

   • Calcium carbonate should not be used in patients with elevated calcium levels 1
   • Caution is advised in patients at risk for vascular calcification 1

4. Pill burden: The need to take multiple tablets with meals can affect adherence 1

Comparison with Other Phosphate Binders

• Calcium acetate: Provides less elemental calcium per phosphate bound compared to calcium carbonate 4, 5

  • Some studies show calcium acetate may have less hypercalcemic effect than calcium carbonate 5
  • May require approximately 4 times less elemental calcium than calcium carbonate for similar phosphate binding 5

• Non-calcium binders (sevelamer, lanthanum): May be preferred in patients with hypercalcemia or at high risk for vascular calcification 1

Monitoring Recommendations

When using calcium carbonate as a phosphate binder:

• Regular monitoring of serum calcium and phosphate levels
• Assessment for signs of hypercalcemia
• Evaluation of calcium-phosphorus product
• Consideration of vascular calcification risk

Bottom Line

Calcium carbonate (Tums) is an effective phosphate binder for lowering phosphate levels in patients with hyperphosphatemia. However, its use should be balanced against the risk of hypercalcemia and vascular calcification, particularly in patients with CKD. The 2017 KDIGO guidelines suggest restricting the dose of calcium-based phosphate binders in adult patients with CKD receiving phosphate-lowering treatment 1.