Nephrology Clinical guideline

Hyperkalemia in Children - Complete Reference

Definitions & Incidence

  • Hyperkalemia defined as plasma potassium > 5.5 mEq/L (mmol/L).
  • Severity: Mild 5.5-6 mEq/L, Moderate 6-7 mEq/L, Severe > 7 mEq/L.
  • Reference ranges strongly vary by age: Age 0-1 days (5-7.5), 2 days-2 months (4-6.2), 3m-14y (3.8-5), >15y (3.5-5.5).
  • Incidence: 22% of all serum electrolyte abnormalities in children. 7% in ED visits for eating disorders.

Pseudohyperkalemia

  • Caused by mechanical hemolysis leaking potassium outside cells in lab tubes (fist-clenching, small needles, pneumatic tubes, extreme leukocytosis/thrombocytosis).
  • Rule out: Obtain repeat specimen within 3 hours. Do not let specimen cool. Do not use tourniquet.
  • Draw simultaneous serum and plasma; if pseudohyperkalemia, plasma K is normal while serum K is elevated.

Diagnostic Pathway & Formulas

  • 1. Measure serum K. Exclude pseudohyperkalemia.
  • 2. Calculate TTKG = (U_K × P_K) / (U_Osm × P_Osm). Only valid if U_Osm > P_Osm.
  • 3. If TTKG > 6-8: Suggests excessive intake, penicillin G, transfusions, rhabdomyolysis/tumor lysis.
  • 4. If TTKG < 6 + low UOP: Suggests Acute Kidney Injury or CKD.
  • 5. If TTKG < 6 + normal UOP: Check Aldosterone. High Aldosterone = Pseudohypoaldosteronism, K-sparing diuretics. Low Aldosterone = Adrenal insufficiency, RTA IV, COX-2, ACEi/ARB, Heparin.
  • 6. Spot Urine K > 40 mEq/L suggests excessive exogenous load or transcellular shift.

ECG Findings & Clinical Signs

  • Rarely symptomatic if K < 6 mEq/L. Manifests mostly if > 7 mEq/L.
  • Neurologic: Muscle pain/cramps, weakness, paresthesia, flaccid paralysis.
  • Mild elevation ECG: Tall and peaked T-waves, shortened QT interval.
  • Moderate elevation ECG: Prolonged PR, decreased P waves.
  • Severe elevation ECG: Flattened broad P waves fused with wide QRS, sinusoidal QRST complex, Ventricular fibrillation/asystole.

Management of Acute Hyperkalemia

  • 1. STABILIZE CARDIAC MEMBRANE: 10% Calcium Gluconate 0.5-1 mL/kg IV (max 20mL). Onset 5m, lasts 30-60m.
  • Alternative for poor cardiac function: 10% Calcium Chloride 0.2 mL/kg IV (max 10mL). Higher risk of vascular necrosis.
  • 2. DRIVE INTRACELLULAR SHIFT: Regular Insulin 0.1 units/kg IV + Dextrose 0.5 g/kg IV. Takes 10-20 mins.
  • Adjunct Shift: Albuterol inhalation (2.5mg if <25kg, 5mg if 25-50kg, 10mg if >50kg). Takes 5-30 mins.
  • Adjunct Shift: Sodium Bicarbonate 1-2 mEq/kg IV (only if concurrent metabolic acidosis). Takes 60 mins.
  • 3. ELIMINATE FROM BODY: Furosemide IV 0.5-1 mg/kg (onset 5m).
  • Sodium Polystyrene Sulfonate (SPS) 1 g/kg rectally/orally. Rectal preferred (20% sorbitol, hold 30m). Decreases K by 0.8 mEq/L.
  • Dialysis for refractory cases or severe kidney failure.

Diagnostic & Management Algorithm

  • Hyperkalemia Stepwise Reversal Protocol: [START] Serum K > 6.5 mEq/L OR ECG changes (Peaked T waves) -> [STEP 1] Membrane stabilization: Calcium Gluconate 10% (100mg/kg over 10m) -> [STEP 2] Intracellular shift: Sodium Bicarbonate (1-2 mEq/kg) AND Albuterol neb -> [STEP 3] Insulin/Glucose drip (0.05 units/kg/hr insulin with D10) -> [STEP 4] Excretion: Furosemide 1mg/kg

References for this guideline are being added; see the methodology for our source hierarchy.

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