K-Phos Neutral: Clinical Uses and Composition
K-Phos Neutral (neutral potassium phosphate) is a combination electrolyte supplement containing both potassium and phosphorus, primarily used to treat or prevent hypophosphatemia and hypocalciuria, while simultaneously providing potassium supplementation. 1, 2
Primary Clinical Indications
Hypophosphatemia Treatment
- K-Phos Neutral effectively corrects mild-to-moderate hypophosphatemia (serum phosphate 1.27-2.48 mg/dL) when administered intravenously at 15 mmol over 3 hours, achieving normalization in 81.5% of cases. 1
- For severe hypophosphatemia (≤1.24 mg/dL), higher doses of 30 mmol are required, though this achieves normalization in only 30% of patients initially, often necessitating repeated supplementation. 1
- Hypophosphatemia is particularly critical in intensive care settings, with prevalence up to 60-80% among ICU patients, and can cause muscle weakness, respiratory failure, cardiac dysfunction, and death if left untreated. 3
Hypercalciuria Management
- Neutral potassium phosphate (UroPhos-K) produces sustained reduction in urinary calcium excretion in patients with absorptive hypercalciuria, decreasing urinary calcium from 264 to 181 mg daily over 4 years of treatment. 2
- The typical dosing regimen is 4 tablets twice daily (each tablet containing 155 mg phosphate and 8 mEq potassium), which maintains bone mineral density at the lumbar spine, femoral neck, and distal radius. 2
- This represents a long-term alternative for hypercalciuric nephrolithiasis patients when thiazide therapy fails. 2
Composition and Formulation
Active Components
- Neutral potassium phosphate contains K₂HPO₄ (neutral form) rather than KH₂PO₄ (acid form), which is critical because the neutral form carries a risk of precipitation when mixed with calcium-containing solutions. 3
- Each tablet typically provides approximately 155 mg phosphate and 8 mEq potassium in slow-release formulations. 2
Metabolic Effects
- Chronic neutral phosphate supplementation stimulates proton secretion in the distal nephron independently of sodium, chloride, and potassium balances, potentially inducing metabolic alkalosis. 4
- This alkalinizing effect occurs through increased titratable acid excretion and elevated urinary PCO₂/HCO₃ ratio, with pH changes of 0.06-0.11 units. 4
Special Population Considerations
Pediatric Parenteral Nutrition
- In preterm infants, phosphorus requirements range from 1.0-2.0 mmol/kg/day during the first days of life, increasing to 1.6-3.5 mmol/kg/day in growing premature infants. 3
- Potassium phosphate can be provided as inorganic salts in parenteral nutrition, though neutral potassium phosphate (K₂HPO₄) has limited use due to precipitation risk with calcium. 3
Renal Replacement Therapy Patients
- In patients on continuous kidney replacement therapy (CKRT), dialysis solutions containing potassium and phosphate should be used rather than intravenous supplementation to prevent electrolyte disorders. 3, 5
- Exogenous intravenous electrolyte supplementation during CKRT is NOT recommended due to severe clinical risks. 3, 5
- Commercial CKRT solutions enriched with potassium and phosphate prevent the 60-80% prevalence of hypophosphatemia and up to 25% prevalence of hypokalemia seen with standard phosphate-free solutions. 3
Chronic Kidney Disease Patients
- Patients with CKD should avoid meat, poultry, and fish products listing phosphorus or potassium additives on ingredient lists, as these significantly increase dietary phosphorus (270 vs 200 mg/100g) and potassium (900 vs 325 mg/100g) loads. 6
- For infants and young children with CKD, 40-120 mg (1-3 mmol/kg/day) of potassium may be a reasonable starting point. 7
Critical Safety Considerations
Precipitation Risk
- The neutral form of potassium phosphate (K₂HPO₄) induces precipitation risk when combined with calcium-containing solutions, limiting its use in parenteral nutrition formulations. 3
- To minimize precipitation, calcium salts should be mixed with amino acids and glucose first, with phosphate salts added at the end of the compounding process. 3
Electrolyte Monitoring
- Plasma phosphate concentration monitoring is critical during treatment, as relative phosphorus deficiency directs available phosphorus to cellular metabolism, reducing bone mineralization or inducing bone demineralization. 3
- In elderly patients receiving oral sodium phosphate preparations, hypokalemia develops in 56% of cases, with 5 patients developing severe hypokalemia (≤3 mEq/L) requiring treatment. 8
- Demented and functionally dependent patients are at higher risk for severe hypokalemia due to intestinal potassium loss with inadequate renal conservation. 8
Contraindications in Renal Impairment
- Potassium supplementation should not be given to patients with significant renal impairment (CrCl <20 mL/min) without careful monitoring, as hyperkalemia can cause cardiac complications. 9
- Assessment of serum electrolytes, phosphorus, and calcium prior to phosphate preparation is advised, with post-procedural assessment and correction required in selected patients. 8