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Electrolyte Replacement Guidelines

Division of Acute Care Surgery

Exclusions

Do not use this protocol for patients with:

  • Hemodialysis / Peritoneal dialysis
  • Acute kidney injury (AKI)
  • Creatinine clearance < 30 mL/min
  • Chronic adrenal insufficiency
  • Electrical burns
  • Rhabdomyolysis
  • Diabetic ketoacidosis (DKA)
  • Crush injury
  • Hypothermia
  • Active transfer orders out of the ICU / Step Down Unit

Potassium Replacement

Always check phosphorus level to determine appropriate potassium product.

Replacement Based on Serum Potassium

Serum K⁺ (mEq/L) Replacement Recheck Level
3.3 – 3.9 40 mEq KCl PO/PT/IV (enteral preferred) With next AM labs
3.0 – 3.2 20 mEq KCl PO/PT/IV × 3 doses (IV preferred) Immediately and with next AM labs
2.6 – 2.9 80 mEq KCl IV and NHO Immediately and with next AM labs
< 2.6 100 mEq KCl IV and NHO Immediately and with next AM labs

*** Consider PO/PT replacement if GI tract available ***

Infusion Guidelines:

  • If central line and continuous cardiac monitoring:
  • Infuse at 20 mEq/hr (max = 40 mEq/hr)
  • If peripheral access only:
  • Infuse at 10 mEq/hr
  • Serum potassium may increase by ~0.25 mEq/L per 20 mEq IV KCl infused.

Magnesium Replacement

Replacement Based on Serum Magnesium

Serum Mg (mg/dL) Replacement Recheck Level
1.3 – 1.9 4 g IV over 4 hours With next AM labs
≤ 1.2 8 g IV over 8 hours 6 hours after replacement

IV Administration:

  • One-time doses using 4 g/100 mL premixed piggybacks
  • Infuse at 1 g per hour

Oral Administration:

  • Elemental magnesium (magnesium oxide) or Milk of Magnesia may be used
  • Note: Oral magnesium is poorly absorbed; diarrhea may limit effectiveness
  • Separate EPIC order must be entered for oral replacement

Phosphorus Replacement

Always look at phosphorus level to determine appropriate potassium product.

Product Reference

Product Phosphate Potassium Sodium
K-Phos Neutral Tablet 250 mg (8 mmol) 1.1 mEq 13 mEq
K Phos Injection (per mL) 3 mmol 4.4 mEq —
Na Phos Injection (per mL) 3 mmol — 4 mEq

Replacement Based on Serum Phosphorus

Serum Phos (mg/dL) Replacement Recheck Level Approx. K⁺ if KPhos Used
2.0 – 2.5 15 mmol KPhos or NaPhos
or
K-Phos Neutral 2 tabs PO/PT q4h × 3 (enteral preferred) With next AM labs ~22 mEq
1.6 – 1.9 30 mmol KPhos or NaPhos
or
K-Phos Neutral 2 tabs PO/PT q4h × 4 (IV preferred) With next AM labs ~44 mEq
< 1.6 45 mmol KPhos or NaPhos 6 hours after replacement ~66 mEq

Notes:

  • Use K Phos if K⁺ < 4.0 mEq/L
  • Use Na Phos if K⁺ ≥ 4.0 mEq/L
  • Pharmacy will dilute in 250–300 mL NS
  • Infuse over 2–6 hours

Calcium Replacement

Replacement based on ionized calcium (iCa⁺⁺):

Ionized Ca (mg/dL) Replacement Recheck Level
3.5 – 3.9 4 g Calcium Gluconate With next AM labs
3.0 – 3.4 6 g Calcium Gluconate 4 hours after replacement
2.5 – 2.9 8 g Calcium Gluconate 4 hours after replacement
< 2.5 10 g Calcium Gluconate and NHO 4 hours after replacement

Infuse at 2 g per hour

References

  1. Zaloga GP, K.R., Bernards WC, Layons AJ. Fluids and Electrolytes. In: Civetta TR, Kirby JM, eds. Critical Care. Vol 1. Philadelphia: Lippincott-Raven; 1997:23.63
  2. Panello JE, Delloyer RP. Critical Care Medicine. 2nd ed. St. Louis: Mosby, Inc.; 2002:1169
  3. Polderman et al. Critical Care Medicine. 2000 Jun; 28(6):2022–2025
  4. Polderman et al. Journal of Neurology. 2001 May; 94(5):697–70

Authors

  • Brad Dennis, MD
  • LeAnne Atchison, PharmD
  • Jennifer Beavers, PharmD

Revisions

  • April 2020
  • April 2022
  • February 2024