Electrolyte Disturbances in Children: Emergency Management Overview

Electrolyte disturbances are among the most common and most dangerous metabolic derangements in critically ill children. They can trigger arrhythmias, compromise cardiac function, and in the worst case cause cardiac arrest. Unlike adult medicine, pediatric electrolyte disturbances require weight-based dosing, age-dependent interpretation of laboratory values, and an understanding of the unique physiological characteristics of childhood. Especially in the context of pediatric cardiac arrest – or when one is imminent – rapid recognition and correction of reversible causes is critical. The AHA guidelines explicitly emphasize electrolyte disturbances as treatable causes in the PALS algorithm (within the "5 T's and 5 H's"). This article provides you with a structured overview of the four most relevant electrolyte disturbances in the pediatric emergency setting: hyperkalemia, hypokalemia, hyponatremia, and hypocalcemia – each with pathophysiology, ECG correlates, clinical assessment, and specific dosing for acute management.

General Principles of Pediatric Electrolyte Diagnostics

Before you treat an electrolyte disturbance, you need to reliably diagnose it. In children, there are some important considerations you should be aware of:

• Blood sampling technique affects results: Hemolysis from difficult venipuncture is common in children and can falsely elevate potassium levels. A capillary blood gas can provide an initial orientation, but pathological values should be confirmed with a venous sample.
• Age-specific reference ranges: Neonates have physiologically higher potassium levels (up to 6.0 mmol/L in the first days of life) and lower sodium levels than older children. Use age-adapted reference ranges.
• Clinical correlation: A 12-lead ECG is mandatory for every suspected electrolyte disturbance. ECG changes may precede clinical symptoms and determine the urgency of therapy.
• Blood gas analysis as initial diagnostics: In the pediatric emergency department or resuscitation bay, a blood gas analysis provides sodium, potassium, ionized calcium, and acid-base status within minutes – often faster than the central laboratory.
• Consider concurrent disturbances: Electrolyte disturbances rarely occur in isolation. Hypokalemia frequently coexists with hypomagnesemia, and hyponatremia with hypoglycemia. Always consider the complete picture.

Hyperkalemia

Definition and Causes

Hyperkalemia in children is defined as a serum potassium > 5.5 mmol/L (> 6.0 mmol/L in neonates). A value > 6.5 mmol/L or any hyperkalemia with ECG changes is considered severe and requires immediate treatment. The most common causes in the pediatric emergency setting are:

• Acute kidney injury (e.g., in HUS, sepsis, dehydration)
• Tumor lysis syndrome
• Massive tissue destruction (burns, crush injuries)
• Adrenal insufficiency (congenital adrenal hyperplasia, Addison's disease)
• Medications (potassium-sparing diuretics, ACE inhibitors, succinylcholine)
• Acidosis (extracellular potassium shift)

ECG Changes

ECG changes roughly correlate with severity but are not always reliably predictable. Typical changes in order of increasing severity:

1. Tall, peaked T-waves (earliest sign, often starting at > 6.0 mmol/L)
2. Flattening of P-waves and prolongation of the PR interval
3. QRS widening
4. Sine wave pattern (merging of QRS and T-wave – pre-terminal)
5. Ventricular fibrillation or asystole

Acute Management – Stepwise Approach

Therapy follows three principles: Myocardial protection → intracellular potassium shift → potassium elimination.

Step 1 – Myocardial stabilization (when ECG changes are present):

• Calcium gluconate 10%: 0.5–1 mL/kg IV (max. 20 mL) over 5–10 minutes with cardiac monitoring. Does not lower potassium but stabilizes the membrane potential. Use with extreme caution in patients on digitalis therapy.

Step 2 – Intracellular potassium shift:

• Insulin-glucose: Regular insulin 0.1 IU/kg IV together with glucose 0.5 g/kg (equivalent to 2.5 mL/kg of 20% glucose or 5 mL/kg of 10% glucose). Close blood glucose monitoring required, onset of action within 15–30 minutes.
• Nebulized salbutamol: 2.5 mg if < 25 kg, 5 mg if > 25 kg. Can lower potassium by 0.5–1 mmol/L. Onset of action within 15–30 minutes. Use with caution in tachyarrhythmias.
• Sodium bicarbonate 8.4%: 1–2 mmol/kg IV slowly. Recommended only when concurrent metabolic acidosis is present, as the potassium-lowering effect is limited at normal pH.

Step 3 – Potassium elimination:

• Furosemide: 1 mg/kg IV (only effective with preserved renal function)
• Sodium polystyrene sulfonate (Resonium): 1 g/kg orally or rectally. Delayed onset of action (hours), therefore not an acute intervention in the strict sense.
• Hemodialysis/hemofiltration: Consider early in treatment-refractory hyperkalemia or anuria.

Hypokalemia

Definition and Causes

Hypokalemia is defined as a serum potassium < 3.5 mmol/L; a value < 2.5 mmol/L is considered severe. In the pediatric emergency context, the most common causes are:

• Gastrointestinal losses (vomiting, diarrhea – especially with gastroenteritis)
• Diuretic therapy (particularly loop diuretics)
• Diabetic ketoacidosis (total body potassium is depleted despite initially normal or elevated serum levels)
• Alkalosis (intracellular shift)
• Refeeding syndrome
• Tubular disorders (e.g., Bartter syndrome)

ECG Changes

• T-wave flattening
• U-waves (positive deflection after the T-wave, particularly in V2–V3)
• ST-segment depression
• QT interval prolongation (risk for Torsades de Pointes)
• Supraventricular and ventricular arrhythmias

Acute Management

• Oral supplementation is sufficient for mild hypokalemia (3.0–3.5 mmol/L) without symptoms: potassium chloride orally 1–2 mmol/kg/day, divided into multiple doses.
• Intravenous supplementation for severe hypokalemia (< 2.5 mmol/L), arrhythmias, or inability to take oral supplementation:
  • Potassium chloride IV: maximum 0.5 mmol/kg/h via a peripheral line (max. concentration 40 mmol/L) or up to 1 mmol/kg/h via a central line with cardiac monitoring.
  • Never administer potassium as a bolus – risk of lethal arrhythmias.
  • Monitor potassium levels every 1–2 hours.
• Rule out/co-treat hypomagnesemia: Hypokalemia is often refractory to treatment as long as concurrent magnesium deficiency is not corrected. Magnesium sulfate 25–50 mg/kg IV (max. 2 g) over 15–30 minutes.

Hyponatremia

Definition and Clinical Relevance

Hyponatremia is defined as a serum sodium < 135 mmol/L. A value < 125 mmol/L or any symptomatic hyponatremia is considered severe. In childhood, hyponatremia is particularly dangerous because the pediatric brain has less room for swelling due to the higher brain-to-skull volume ratio. Even moderate hyponatremia can lead to seizures and cerebral edema in children.

Common Causes in the Pediatric Setting

• Hypovolemic: Gastroenteritis with hypotonic rehydration, salt-wasting syndrome
• Euvolemic: SIADH (e.g., in CNS infections, postoperatively, ventilation-associated)
• Hypervolemic: Nephrotic syndrome, heart failure, hepatic insufficiency
• Iatrogenic: Hypotonic IV solutions – a classic and preventable error in pediatrics. Isotonic solutions are the standard for maintenance fluid therapy.

Clinical Symptoms

Symptoms correlate with both the absolute value and the rate of sodium decline:

• Mild hyponatremia (130–135 mmol/L): often asymptomatic
• Moderate hyponatremia (125–130 mmol/L): nausea, headache, lethargy
• Severe hyponatremia (< 125 mmol/L): seizures, altered consciousness, cerebral edema, respiratory arrest

Acute Management

For symptomatic hyponatremia with seizures or altered consciousness:

• Hypertonic saline (3% NaCl): 2–5 mL/kg IV over 10–20 minutes. May be repeated once if symptoms persist.
• The goal is to raise serum sodium by 4–6 mmol/L in the first 1–2 hours – just enough to break the cerebral symptoms.
• Maximum correction rate: No more than 8–10 mmol/L in the first 24 hours. Overly rapid correction carries the risk of osmotic demyelination syndrome (central pontine myelinolysis), although this risk is lower in children than in adults.
• Monitor sodium every 2 hours.

For asymptomatic hyponatremia:

• Identifying the underlying cause takes priority.
• Fluid restriction for SIADH.
• Isotonic volume administration for hypovolemia.
• Aim for slow correction over 24–48 hours.

Practical tip: The required sodium amount can be approximately calculated: Na⁺ deficit (mmol) = 0.6 × body weight (kg) × (target Na⁺ − current Na⁺). This formula serves as a guide; actual therapy is guided by frequent laboratory monitoring.

Hypocalcemia

Definition and Pediatric Considerations

The clinically relevant value is ionized calcium (iCa²⁺), not total calcium. Hypocalcemia is defined as an iCa²⁺ < 1.1 mmol/L (neonates < 1.0 mmol/L). Total calcium is influenced by albumin binding and is often misleadingly low in critically ill children with hypoalbuminemia.

Common Causes

• Neonatal hypocalcemia (early: within the first 48 hours of life in preterm infants, infants of diabetic mothers; late: with high phosphate intake)
• Vitamin D deficiency
• Hypoparathyroidism (e.g., DiGeorge syndrome)
• Massive blood transfusions (citrate toxicity)
• Sepsis
• Tumor lysis syndrome (hyperphosphatemia → calcium precipitation)

Clinical Symptoms and ECG

• Neuromuscular: Tetany, carpopedal spasms, laryngospasm, seizures. In infants, symptoms are often nonspecific: jitteriness, poor feeding, apneas.
• Cardiovascular: Hypotension, heart failure.
• ECG: Prolongation of the QTc interval – this is the most reliable ECG sign. Rarely, arrhythmias up to cardiac arrest.

Acute Management

• Calcium gluconate 10%: 0.5–1 mL/kg (equivalent to 0.11–0.22 mmol/kg elemental calcium) IV over 10–20 minutes. Heart rate monitoring is mandatory – stop the infusion if bradycardia occurs.
• Calcium chloride 10%: 0.2 mL/kg IV (contains three times more elemental calcium than calcium gluconate). Due to venous irritation and risk of tissue necrosis with extravasation, preferably administered via a central line. During resuscitation, calcium chloride may also be given peripherally.
• Maintenance: After bolus therapy, calcium gluconate 10% as a continuous infusion: 5 mL/kg/24 h, target iCa²⁺ > 1.1 mmol/L.
• Check magnesium levels: Hypomagnesemia causes functional hypoparathyroidism and renders hypocalcemia refractory to treatment.

Important in the resuscitation setting: The AHA recommends calcium administration in pediatric cardiac arrest only for documented hypocalcemia, hyperkalemia, hypermagnesemia, or calcium channel blocker overdose – not routinely.

Electrolyte Disturbances in the PALS Algorithm: Clinical Integration

In the PALS algorithm for cardiac arrest, electrolyte disturbances are among the reversible causes that must be systematically evaluated. Key points:

• In every pediatric cardiac arrest, a blood gas analysis should be obtained as early as possible – it provides potassium, sodium, ionized calcium, and pH within minutes.
• PEA and asystole are the typical rhythms in severe hyperkalemia – think of this especially in children with known renal disease, dialysis dependence, or after chemotherapy.
• Polymorphic ventricular tachycardia (Torsades de Pointes) should prompt consideration of hypokalemia, hypomagnesemia, or hypocalcemia. Treatment of choice: magnesium sulfate 25–50 mg/kg IV (max. 2 g) as a bolus.
• Severe hyponatremia with cerebral edema can lead to herniation, respiratory arrest, and consequently cardiac arrest – a scenario that occurs in children with CNS pathology or after iatrogenic hypotonic fluid administration.

Summary: Emergency Dosing Reference Table

Electrolyte Disturbance	Medication	Dosing	Administration
Hyperkalemia	Calcium gluconate 10%	0.5–1 mL/kg (max. 20 mL)	IV over 5–10 min
Hyperkalemia	Insulin + glucose	0.1 IU/kg + 0.5 g/kg glucose	IV
Hyperkalemia	Salbutamol	2.5–5 mg	Nebulized
Hypokalemia	KCl IV	max. 0.5 mmol/kg/h peripheral	IV continuous infusion
Hyponatremia	3% NaCl	2–5 mL/kg	IV over 10–20 min
Hypocalcemia	Calcium gluconate 10%	0.5–1 mL/kg	IV over 10–20 min
Hypocalcemia (resuscitation)	Calcium chloride 10%	0.2 mL/kg	IV
Torsades de Pointes	Magnesium sulfate	25–50 mg/kg (max. 2 g)	IV bolus

Practical Training

Electrolyte disturbances in children require rapid recognition, reliable dose calculation, and a structured approach – skills that are best trained in realistic simulation scenarios. In the PALS course (Pediatric Advanced Life Support) from Simulation Tirol, you practice exactly these situations: from ECG interpretation to weight-based medication dosing to integrating electrolyte correction into the resuscitation algorithm. You work through concrete case scenarios, receive direct feedback, and gain the confidence you need in a real emergency. All information about the next PALS course can be found on our website.