What is the appropriate IV potassium replacement protocol for a 3-year-old child weighing 13 kg with severe hypokalemia (potassium level of 2 mEq/L)?

IV Potassium Correction for Severe Pediatric Hypokalemia

For a 3-year-old child (13 kg) with severe hypokalemia (K+ = 2.0 mEq/L), administer IV potassium chloride at 0.25 mmol/kg over 30 minutes (3.25 mEq total dose), followed by continuous infusion at 0.25 mEq/kg/hour with continuous cardiac monitoring until potassium normalizes above 2.5 mEq/L, then transition to oral replacement. 1, 2

Immediate Assessment and Pre-Treatment Checks

Before initiating potassium replacement, you must:

• Verify adequate urine output (≥0.5 mL/kg/hour = ≥6.5 mL/hour for this child) to confirm renal function 1, 2
• Check and correct magnesium levels first - hypomagnesemia is the most common reason for refractory hypokalemia and must be corrected before potassium levels will normalize, targeting magnesium >0.6 mmol/L 1, 3, 2
• Obtain immediate ECG - severe hypokalemia at this level causes ST-segment depression, T-wave flattening, prominent U waves, and long QTc that can progress to life-threatening ventricular arrhythmias 4, 5
• Establish continuous cardiac monitoring - life-threatening arrhythmias including ventricular fibrillation can occur at any time during replacement 2, 4

Initial IV Replacement Protocol

First Dose (Emergency Correction)

Administer 0.25 mmol/kg (0.25 mEq/kg) potassium over 30 minutes 1

For this 13 kg child:

• Dose = 3.25 mEq potassium chloride
• Infuse over 30 minutes via peripheral IV
• Concentration should not exceed 40 mEq/L 6, 5

This guideline from severe malaria management in children is directly applicable to severe hypokalemia in pediatrics 1.

Continuous Infusion (After Initial Bolus)

Following the initial dose, begin continuous infusion at 0.25 mEq/kg/hour (3.25 mEq/hour for this child) 2

• Maximum peripheral line rate: 10 mEq/hour - this child's calculated rate of 3.25 mEq/hour is well within safe limits 6
• Maximum concentration via peripheral line: 40 mEq/L 6, 5
• Total 24-hour dose should not exceed 200 mEq (15.4 mEq/kg for this child) 6

Monitoring Protocol

Immediate Phase (First 2-4 Hours)

• Recheck serum potassium within 1-2 hours after initial bolus to assess response and avoid overcorrection 3, 2
• Continue cardiac monitoring continuously - watch for peaked T waves, widened QRS, or arrhythmias indicating overcorrection 2
• Monitor for signs of phlebitis at IV site due to potassium's irritating properties 5

Ongoing Monitoring

• Check potassium every 2-4 hours during active IV replacement until stable above 2.5 mEq/L 1, 2
• Once K+ reaches 2.5-3.0 mEq/L, slow infusion rate and prepare for transition to oral therapy 6, 5
• Monitor renal function, calcium, and magnesium every 2-4 hours initially 1

Transition to Oral Therapy

Once potassium reaches >2.5 mEq/L and child tolerates oral intake, transition to oral potassium chloride syrup 2, 7

• Oral dose: 1-3 mmol/kg/day (13-39 mmol/day for this child) divided into 2-4 doses 2
• Standard concentration: 6 mg/mL potassium chloride syrup 3, 2
• Give with or after meals to minimize GI irritation 2
• Mix with juice or water to improve palatability 2

Critical Concurrent Interventions

Magnesium Correction (Essential)

If magnesium <0.6 mmol/L, administer magnesium sulfate 25-50 mg/kg IV over 2-4 hours 8

• For this 13 kg child: 325-650 mg magnesium sulfate over 2-4 hours
• Hypomagnesemia makes hypokalemia resistant to correction regardless of how much potassium you give 1, 3, 2
• Approximately 40% of hypokalemic patients have concurrent hypomagnesemia 3

Identify Underlying Cause

Common causes in this age group include:

• Gastrointestinal losses (diarrhea, vomiting) - most common in young children 9, 5
• Inadequate dietary intake 2, 5
• Medications (diuretics if applicable) 9, 5
• Diabetic ketoacidosis - total body deficit 3-5 mEq/kg despite normal initial levels 2, 7

Special Considerations for This Age Group

Fluid Management

• Use isotonic fluids (0.9% NaCl or Lactated Ringer's) as base solution for potassium administration 1
• Add 20-30 mEq/L potassium to maintenance fluids once initial correction achieved 2, 7
• Consider 2/3 KCl and 1/3 KPO4 if concurrent phosphate depletion suspected 1, 2

Dietary Counseling (For Ongoing Management)

Once oral intake established, encourage:

• Bananas, oranges, potatoes, yogurt - age-appropriate potassium-rich foods 2
• Breast milk contains 14 mmol/L potassium if still breastfeeding 2
• Standard formulas contain 18-19 mmol/L potassium 2

Critical Pitfalls to Avoid

• Never supplement potassium without checking and correcting magnesium first - this is the single most common reason for treatment failure 3, 2
• Never administer potassium as rapid bolus except in life-threatening cardiac arrest (which is ill-advised even then) 3, 5
• Never exceed 10 mEq/hour via peripheral line without central access and intensive monitoring 6
• Do not use potassium citrate or non-chloride salts if metabolic alkalosis present 2
• Avoid potassium-containing salt substitutes during active supplementation 2

When to Escalate Care

Consider ICU transfer if:

• ECG shows life-threatening arrhythmias (ventricular tachycardia, torsades de pointes) 4, 5
• Severe neuromuscular symptoms (paralysis, respiratory muscle weakness) 5
• Potassium fails to rise despite adequate replacement and magnesium correction 3
• Concurrent severe metabolic derangements (pH <7.2, glucose >400 mg/dL suggesting DKA) 7

Target Potassium Range

Aim for serum potassium 4.0-5.0 mEq/L 3, 2

• This range minimizes cardiac risk in all patients 3
• Once stable in this range, continue oral supplementation 1-3 mmol/kg/day divided doses 2
• Recheck potassium and renal function within 3-7 days after starting oral therapy 2