Hypophosphatemia

Background

  • Phosphate required in function of all hematologic cells (RBCs, WBCs, platelets)

Clinical Features

Differential Diagnosis

Causes of Hypophosphatemia

  • Internal redistribution
  • Decreased intestinal absorption
    • Inadequate intake
    • Antacids containing aluminum or magnesium
    • Steatorrhea and/or chronic diarrhea
  • Increased urinary excretion
  • Renal replacement therapy (dialysis)

Evaluation

  • 2.5-2.8 Mild
  • 1.0-2.5 Moderate
  • <1.0 Severe

Management

  • Mild-moderate
    • KPhos /neutra phos PO
  • Severe
    • KPhos 2.5-5mg/kg IV over 6hr

Harbor UCLA Adult Treatment Guidelines

Serum phosphate 1mg/dl to 2mg/dl

  • Able to take PO
    • Minimize or eliminate all dextrose-containing IV solutions
    • Aggressively treat acidosis
    • 1 tab K-phos neutral 250mg Q hour x 5 doses
      • Each tab contains phosphorus 8 mmol, Na 13 mEq, K1.1 mEq
    • Recheck serum phosphate after last dose, and repeat dosing if continues to be <2mg/dl
  • NOT able to take PO
    • Minimize or eliminate all dextrose-containing IV solutions
    • Aggressively treat acidosis
    • Give 15 mmol of IV potassium phosphate over 2.5 hours (contains 22 mEq K)
      • Peripheral administration may cause burning at injection site
      • Consider central venous administration, if available
      • Repeat dosing regimen if serum phosphate remains <2mg/dl

Serum phosphate <1mg/dl

  • Minimize or eliminate all dextrose-containing IV solutions
    • Exceptions: vasopressors, sedatives, analgesics, antibiotics, blood products, NS
  • Aggressively treat acidosis
  • Give 45 mmol of IV potassium phosphate over 7 hours (contains 66 mEq of K)
    • Peripheral administration may cause burning at injection site
    • Consider central venous administration, if available
  • If patient can tolerate PO, ALSO follow steps 1 above
  • Recheck serum phosphate after infusion
    • Repeat IV administration if <1mg/dl
    • Consider oral administration if >1mg and <2mg/dl

Disposition

See Also