Hyperkalemia in Children

Hyperkalemia in Children Introduction Etiology Clinical Presentation Diagnosis Management Complications

Introduction to Hyperkalemia in Children

Hyperkalemia is defined as a serum potassium level greater than 5.5 mEq/L in children. It is a potentially life-threatening electrolyte imbalance that requires prompt recognition and treatment. The normal range of serum potassium in children varies slightly by age:

• Newborns: 3.7-5.9 mEq/L
• Infants: 4.1-5.3 mEq/L
• Children: 3.4-4.7 mEq/L

Hyperkalemia is more common in neonates due to immature renal function and the shift from intrauterine to extrauterine life. In older children, it is often associated with underlying conditions affecting potassium homeostasis.

Etiology of Hyperkalemia in Children

The causes of hyperkalemia in children can be categorized into three main mechanisms:

1. Increased Potassium Intake:
   • Excessive dietary intake (rare in children with normal renal function)
   • Iatrogenic causes (e.g., rapid intravenous potassium administration)
   • Blood transfusions (particularly with stored blood)
2. Transcellular Shift of Potassium:
   • Metabolic acidosis
   • Insulin deficiency or resistance
   • Beta-blocker toxicity
   • Tissue breakdown (rhabdomyolysis, tumor lysis syndrome)
   • Hereditary periodic paralysis
3. Decreased Renal Excretion:
   • Acute or chronic kidney disease
   • Obstructive uropathy
   • Hypoaldosteronism or pseudohypoaldosteronism
   • Medications (ACE inhibitors, ARBs, potassium-sparing diuretics, NSAIDs)
   • Congenital adrenal hyperplasia

In neonates, common causes include prematurity, perinatal asphyxia, and certain medications used in the NICU.

Clinical Presentation of Hyperkalemia in Children

The clinical manifestations of hyperkalemia can range from asymptomatic to life-threatening arrhythmias. Symptoms and signs may include:

• Neuromuscular:
  • Muscle weakness or paralysis
  • Paresthesias
  • Areflexia
• Gastrointestinal:
  • Nausea
  • Vomiting
  • Abdominal pain
• Cardiovascular:
  • Palpitations
  • Bradycardia
  • Hypotension

In severe cases, hyperkalemia can lead to cardiac arrhythmias and cardiac arrest. The severity of symptoms often correlates with the rate of increase in serum potassium rather than the absolute level.

Diagnosis of Hyperkalemia in Children

Diagnosis of hyperkalemia involves both laboratory tests and clinical evaluation:

1. Serum Potassium Measurement:
   • Confirm with repeat testing to rule out pseudohyperkalemia
   • Consider simultaneous plasma potassium measurement
2. Electrocardiogram (ECG):
   • Peaked T waves (earliest sign)
   • Prolonged PR interval
   • Widened QRS complex
   • Loss of P waves
   • Sine wave pattern (in severe cases)
3. Additional Laboratory Tests:
   • Complete blood count (to assess for hemolysis)
   • Renal function tests (BUN, creatinine)
   • Arterial blood gas (to assess acid-base status)
   • Urinary potassium excretion
   • Serum calcium and magnesium levels
4. Clinical Evaluation:
   • Detailed history (including medication use and dietary intake)
   • Physical examination (focusing on neuromuscular and cardiovascular systems)

It's crucial to differentiate true hyperkalemia from pseudohyperkalemia, which can occur due to hemolysis during blood collection or prolonged storage of samples.

Management of Hyperkalemia in Children

The management of hyperkalemia in children depends on the severity and underlying cause. Treatment strategies include:

1. Emergency Measures (for severe hyperkalemia or ECG changes):
   • Calcium gluconate: 10% solution, 0.5-1 mL/kg IV over 5-10 minutes (max 10 mL)
   • Insulin and glucose: Regular insulin 0.1 units/kg IV with glucose 0.5-1 g/kg
   • Inhaled beta-2 agonists: Albuterol 2.5-5 mg nebulized
   • Sodium bicarbonate: 1-2 mEq/kg IV over 5-10 minutes (if metabolic acidosis present)
2. Potassium Removal:
   • Loop diuretics: Furosemide 1-2 mg/kg IV
   • Cation exchange resins: Sodium polystyrene sulfonate 1 g/kg orally or rectally
   • Hemodialysis (in severe cases or renal failure)
3. Ongoing Management:
   • Identify and treat underlying cause
   • Adjust medications that may contribute to hyperkalemia
   • Dietary potassium restriction as needed
   • Regular monitoring of serum potassium levels

It's important to note that treatment should be tailored to the individual patient, considering their age, weight, and underlying conditions. Close monitoring of ECG and serum potassium levels is essential during treatment.

Complications of Hyperkalemia in Children

Untreated or severe hyperkalemia can lead to several complications:

• Cardiac Arrhythmias:
  • Ventricular fibrillation
  • Ventricular tachycardia
  • Asystole
• Neuromuscular Complications:
  • Ascending paralysis
  • Respiratory failure
• Metabolic Acidosis: Can worsen existing hyperkalemia
• Acute Kidney Injury: As both a cause and consequence of hyperkalemia
• Treatment-Related Complications:
  • Hypoglycemia (from insulin treatment)
  • Hypocalcemia (from sodium bicarbonate administration)
  • Fluid overload (from IV therapies)

Long-term complications can arise from recurrent episodes of hyperkalemia, especially in children with chronic conditions affecting potassium homeostasis. These may include growth retardation, developmental delays, and chronic kidney disease progression.

Hyperkalemia in Children

1. What is hyperkalemia?
   Hyperkalemia is a condition characterized by elevated levels of potassium in the blood, typically above 5.5 mEq/L.
2. Which of the following is NOT a common cause of hyperkalemia in children?
   Excessive consumption of dairy products
3. What is the most common cause of hyperkalemia in children?
   Renal dysfunction or failure
4. Which medication class can contribute to hyperkalemia?
   ACE inhibitors
5. What is the normal range of serum potassium in children?
   3.5-5.5 mEq/L
6. Which of the following is an early ECG change associated with hyperkalemia?
   Tall, peaked T waves
7. What is the most serious complication of severe hyperkalemia?
   Cardiac arrhythmias and potential cardiac arrest
8. Which organ system is primarily responsible for potassium regulation?
   The renal system (kidneys)
9. What is the role of insulin in managing hyperkalemia?
   Insulin promotes the intracellular shift of potassium, lowering serum levels
10. Which of the following is NOT a symptom of hyperkalemia in children?
    Increased urination
11. What is the mechanism of action of calcium gluconate in treating hyperkalemia?
    It stabilizes cardiac cell membranes, reducing the risk of arrhythmias
12. Which laboratory test is essential for diagnosing hyperkalemia?
    Serum potassium level
13. What is the role of sodium polystyrene sulfonate (Kayexalate) in treating hyperkalemia?
    It binds potassium in the intestine, promoting its excretion
14. Which of the following conditions can cause pseudohyperkalemia?
    Hemolysis of blood sample during collection or processing
15. What is the primary goal of emergency treatment for severe hyperkalemia?
    Cardiac membrane stabilization and reduction of serum potassium levels
16. Which electrolyte imbalance often accompanies hyperkalemia in renal failure?
    Metabolic acidosis
17. What is the mechanism of action of beta-2 agonists (e.g., albuterol) in treating hyperkalemia?
    They promote intracellular shift of potassium
18. Which of the following is a late ECG change in severe hyperkalemia?
    Sine wave pattern
19. What is the role of loop diuretics in managing hyperkalemia?
    They increase urinary excretion of potassium
20. Which endocrine disorder can lead to hyperkalemia in children?
    Addison's disease (adrenal insufficiency)
21. What is the most appropriate initial action when severe hyperkalemia is suspected?
    Obtain an ECG and serum potassium level
22. Which of the following is NOT a common ECG change in hyperkalemia?
    Prolonged QT interval
23. What is the mechanism of action of sodium bicarbonate in treating hyperkalemia?
    It promotes intracellular shift of potassium by increasing blood pH
24. Which of the following conditions can cause transient hyperkalemia in newborns?
    Non-oliguric hyperkalemia of prematurity
25. What is the role of dietary modification in managing chronic hyperkalemia?
    Restricting high-potassium foods to reduce overall potassium intake
26. Which medication used to treat hyperkalemia can cause bowel necrosis as a side effect?
    Sodium polystyrene sulfonate (Kayexalate)
27. What is the most appropriate treatment for mild, asymptomatic hyperkalemia?
    Dietary potassium restriction and addressing underlying causes
28. Which of the following is a risk factor for developing hyperkalemia in children?
    Chronic kidney disease
29. What is the role of calcium resonium in managing hyperkalemia?
    It exchanges calcium for potassium in the intestine, promoting potassium excretion
30. Which of the following is NOT a common cause of transcellular potassium shift resulting in hyperkalemia?
    Alkalosis

Further Reading

• Hyperkalemia in Children: Pathophysiology, Evaluation, and Management
• Potassium Homeostasis in Health and Disease: A Scientific Workshop Cosponsored by the National Kidney Foundation and the American Society of Hypertension
• UpToDate: Hyperkalemia in children: Etiology and clinical manifestations
• Medscape: Pediatric Hyperkalemia