How to correct severe hypokalemia and hypocalcemia?

Correction of Severe Hypokalemia (K+ 1.5 mEq/L) and Severe Hypocalcemia (Ca <1 mmol/L)

For potassium 1.5 mEq/L with severe hypocalcemia, immediate IV correction is mandatory with continuous cardiac monitoring, as both deficiencies create life-threatening arrhythmia risk and must be corrected simultaneously while addressing underlying magnesium deficiency.

Immediate Assessment and Monitoring

• Obtain 12-lead ECG immediately to assess for hypokalemia changes (U waves, T-wave flattening, ST depression, prolonged QT) and hypocalcemia changes (prolonged QT interval) 1, 2
• Establish continuous cardiac monitoring before initiating any IV electrolyte replacement, as rapid correction can precipitate fatal arrhythmias 3, 4
• Check serum magnesium level urgently, as hypomagnesemia commonly accompanies both deficiencies and prevents successful potassium correction 5, 2
• Assess for cardiac glycoside use (digoxin), as calcium administration with concurrent digitalis therapy can cause synergistic arrhythmias 6

Calcium Correction Protocol (First Priority)

Correct calcium first or simultaneously with potassium, as severe hypocalcemia (<1 mmol/L or <2 mmol/L) poses immediate risk of seizures, tetany, and cardiac arrest.

• Administer 10% calcium gluconate 0.3 mL/kg IV over 30 minutes for total calcium <2 mmol/L 1
• For adults, this translates to 15-30 mL of 10% calcium gluconate IV over 2-5 minutes for symptomatic hypocalcemia, followed by continuous infusion 1
• Use a secure IV line and administer via central route when possible to avoid tissue necrosis from extravasation 6
• Monitor for bradycardia, hypotension, and arrhythmias during calcium infusion; slow or stop infusion if these occur 6
• Recheck serum calcium every 4-6 hours during intermittent infusions or every 1-4 hours during continuous infusion 6

Critical Calcium Administration Warnings

• If patient is on digoxin, give calcium very slowly in small amounts with close ECG monitoring due to synergistic arrhythmia risk 6, 1
• Do not mix calcium with phosphate or bicarbonate-containing fluids, as precipitation will occur 6
• Stop infusion immediately if extravasation occurs to prevent calcinosis cutis and tissue necrosis 6

Potassium Correction Protocol

With K+ 1.5 mEq/L (severe hypokalemia <2.5 mEq/L), IV replacement is required, but bolus administration is contraindicated even in cardiac arrest.

Severe Hypokalemia (<2 mEq/L) with ECG Changes

• Administer IV potassium at rates up to 40 mEq/hour when serum K+ <2 mEq/L with ECG changes or muscle paralysis 3
• Maximum 400 mEq over 24 hours for severe cases with continuous ECG monitoring 3
• Use central venous access whenever possible for concentrations >10 mEq/100mL to minimize pain and extravasation risk 3
• Recheck serum potassium every 1-2 hours during aggressive replacement to avoid rebound hyperkalemia 3, 4

Standard IV Potassium Replacement

• For K+ 2-2.5 mEq/L, administer 10 mEq/hour (maximum 200 mEq/24 hours) if serum K+ >2.5 mEq/L 3
• Dilute potassium chloride appropriately and use calibrated infusion device at controlled rate 3
• Never administer potassium as IV bolus, even in cardiac arrest, as this is contraindicated and can cause cardiac arrest 1, 2

Magnesium Correction (Essential for Success)

Hypokalemia is often refractory to treatment without correcting concurrent hypomagnesemia, which is present in most cases of severe electrolyte depletion.

• Administer 50% magnesium sulfate 0.2 mL/kg IV over 30 minutes if magnesium <0.75 mmol/L 1
• Correct magnesium deficiency before or simultaneously with potassium, as hypomagnesemia impairs cellular potassium uptake 5, 2
• For adults, typical dose is 2-4 grams (16-32 mEq) magnesium sulfate IV over 1-2 hours 2

Target Levels and Monitoring

• Target serum potassium: 4.0-4.5 mEq/L (or 4.5-5.0 mEq/L if patient has heart failure on mineralocorticoid receptor antagonists) 5, 2
• Target serum calcium: >2 mmol/L (>8 mg/dL) 1
• Monitor serum potassium every 4-6 hours until stable, then daily 2
• Monitor serum calcium every 4-6 hours during active replacement 6
• Continuous ECG monitoring is mandatory throughout aggressive electrolyte replacement 3, 4

Identify and Address Underlying Causes

• Evaluate for gastrointestinal losses (diarrhea, vomiting, nasogastric suction) as common cause of combined deficiencies 4, 7
• Review medications: discontinue thiazide diuretics, loop diuretics temporarily until electrolytes normalize 2, 4
• Assess renal function and acid-base status to determine if renal wasting is contributing 4
• Check for chronic diarrhea or malabsorption, which causes both potassium and calcium losses 2

Critical Pitfalls to Avoid

• Never correct severe hypokalemia rapidly without cardiac monitoring, as rebound hyperkalemia or arrhythmias can occur 3, 4
• Do not attempt potassium correction without checking magnesium first, as replacement will fail if hypomagnesemia persists 5, 2
• Avoid calcium administration in patients on digoxin without extreme caution and slow infusion, as fatal arrhythmias can result 6, 1
• Do not use peripheral IV for high-concentration potassium (>10 mEq/100mL); use central access 3
• Never give IV potassium as bolus, even in emergencies; slow infusion is required 1, 2

Transition to Maintenance Therapy

• Once K+ >3.0 mEq/L and patient stable, transition to oral potassium 40-100 mEq/day in divided doses 2, 4
• Continue oral calcium supplementation 1-2 grams elemental calcium daily after acute correction 6
• Maintain magnesium repletion with oral supplementation 400-800 mg daily 2
• Recheck electrolytes in 5-7 days after transitioning to oral therapy 2