Electrolyte Repletion Guide

General Considerations

  • Use oral replacement when possible (IV if symptomatic or NPO)
  • Consider fluid load of IV electrolyte replacement. For example:
    • KCl 10 mEq IV = 200 mL fluid
    • Mg Sulfate 1 g IV = 100 mL fluid.
  • Use with caution in patients with renal failure
Current Potassium Level (mmol/L) Potassium Cl/Water 10mEq/100mL Potassium Chloride PO
(liquid or tablet)		 Lab Monitoring
3.6 - 3.9 10 mEq IV over 1 HR x 1-2 dose 20 mEq KCl PO x 1 dose Recheck daily
3.4 - 3.5 10 mEq IV over 1 HR x 2 doses 60 mEq KCl PO x 1 dose
3.0 - 3.3 10 mEq IV over 1 HR x 4 doses 40 mEq KCl PO Q2H x 2 doses Recheck serum potassium level 2 hours after repletion complete
< 3.0 10 mEq IV over 1 HR x 6 doses 40 mEq KCl PO Q2H x 2 doses*
  • Goal for cardiac patients is K > 3.9. Goal for all others is normal ref range
  • For K < 3 and symptomaic, place on telemetry during repletion until K > 3.5 and asymptomatic.
  • Expected rise of 0.1 for every 10 mEq KCl

* May require additional 40 mEq

Current Mg Level (mg/dL) Magnesium Sulfate/D5W 1g/100mL Magnesium Oxide (tablet) Lab Monitoring
1.8 - 1.9 2 g over 2 HR 400 mg PO Recheck daily
1.6 - 1.79 3 g over 3 HR
< 1.6 4 g over 4 HR (Use IV instead) Recheck serum Mg level 2 HR after infusion complete
Oral Dosing Phopha Neutral 250 mg Tablet (Contains 8 mmol phos, 5.8 mEq Na, and 1.1 mEq K)
Current Phos Level (mg/dL) Patient's Wt (kg) Lab Monitoring
< 60 kg ≥ 60 kg
≥ 1.5 2 tablets Q6-8H x 3 3 tablets Q6-8H x 3 Recheck serum Phos level 2 HR after last dose
< 1.5 2 tablets Q6H x 4 3 tablets Q6H x 4 doses
  • Reduce dose by ~50% if CrCl < 30 mL/min
  • When asymptomatic, replace with oral phosphate when less than 2 mg/dL
  • When symptomatic, treat with oral phos when between 1.0 - 1.9 mg/dL. Use IV if < 1.0 mg/dL
IV Postassium Phosphate 3 mmol/mL (diluted in 250 mL)
Current Phos Level (mg/dL) Patient's Wt (kg) Lab Monitoring
< 60 kg ≥ 60 kg
≥ 1.25 10 mmol 20 mmol Recheck serum Phos level 2 HR after last dose
< 1.25 20 mmol 40 mmol
  • Infusion rate: 4-5 mmol/HR
  • Reduce dose by ~50% if CrCl < 30 mL/min
  • If both potassium and phosphorus replacement required, subtract the mEq of potassium given as potassium phosphate from total amount of potassium required. (Conversion: 3 mmols KPO4 = 4.4 mEq K+)
  • Sodium phosphates 3 mmol/mL use for K > 4 & Na < 145
  • Potassium phosphate 3 mmol/mL use for K < 4 & Na > 140
Calcium Gluconate
Current Ionized Ca Level (mmol/L) Dose Lab Monitoring
0.87 - 0.97 4 g Next AM Lab
0.75 - 0.86 6 g 4 HR after repletion
0.62 - 0.74 8 g 4 HR after repletion
< 0.62 10 g 4 HR after repletion
  • Infusion rate: 2 g/HR
  • Caution in dialysis patients or those with a CrCl < 20