What is considered hyperkalemia (elevated potassium level) in an adult?

Hyperkalemia: Definition and Clinical Implications

Hyperkalemia is defined as a serum potassium level greater than 5.0 mmol/L in adults, with levels above 7.0-7.5 mmol/L or those associated with ECG changes requiring immediate intervention. 1

Classification of Hyperkalemia

Hyperkalemia can be categorized by severity:

• Mild: >5.0 to <5.5 mmol/L
• Moderate: 5.5 to 6.0 mmol/L
• Severe: >6.0 mmol/L 1

Risk Factors and Clinical Significance

Hyperkalemia is particularly common in:

• Chronic kidney disease (CKD), especially when GFR decreases to <10-15 mL/min/1.73 m² 1
• Heart failure
• Diabetes mellitus
• Patients taking certain medications (RAAS inhibitors, potassium-sparing diuretics)

The clinical significance of hyperkalemia lies in its potential to cause:

• Cardiac arrhythmias
• Muscle weakness or paralysis
• Sudden cardiac death

Diagnostic Considerations

When evaluating elevated potassium:

• Always verify with a second sample to rule out pseudohyperkalemia from hemolysis during phlebotomy 1
• Assess ECG for characteristic changes (peaked T waves, widened QRS, prolonged PR interval)
• Consider the clinical context and medication review

Management Algorithm

1. Immediate Management for Severe Hyperkalemia (>7.0-7.5 mmol/L or with ECG changes)

• Calcium gluconate (100-200 mg/kg via slow infusion with ECG monitoring) for cardiac membrane stabilization 1
• Insulin (0.1 U/kg IV) with glucose (25% dextrose 2 mL/kg) to shift potassium intracellularly 1
• Sodium bicarbonate (1-2 mEq/kg IV) to induce influx of potassium into cells 1
• Note: Do not administer sodium bicarbonate and calcium through the same line 1

2. Management of Non-Emergent Hyperkalemia

• Sodium polystyrene sulfonate (1 g/kg with sorbitol) orally or rectally (avoid rectal route in neutropenic patients) 1
• Consider newer potassium binders if available (patiromer or sodium zirconium cyclosilicate) 2
• Eliminate oral and IV sources of potassium 1
• Review and adjust medications that contribute to hyperkalemia

3. Prevention and Long-term Management

• Regular monitoring of serum potassium in high-risk patients
• Dietary potassium restriction (<2,000-3,000 mg/day) in adults with CKD and hyperkalemia 1
• Avoid potassium-containing salt substitutes 1
• Careful use of RAAS inhibitors with close monitoring

Medication Considerations

Common medications that can cause hyperkalemia include:

1. RAAS inhibitors (ACE inhibitors, ARBs, direct renin inhibitors)
2. Potassium-sparing diuretics (spironolactone, eplerenone, triamterene, amiloride)
3. NSAIDs
4. Beta-blockers
5. Calcineurin inhibitors (cyclosporine, tacrolimus)
6. Trimethoprim-sulfamethoxazole 1

When using aldosterone antagonists:

• Check potassium and renal function within 3 days and at 1 week after initiation
• Monitor at least monthly for the first 3 months and every 3 months thereafter 1
• Discontinue or reduce dose if potassium exceeds 5.5 mEq/L 1

Special Considerations

• In patients with CKD, potassium restriction should be individualized based on severity of hyperkalemia and stage of kidney disease 1
• Patients with heart failure on RAAS inhibitors require particularly close monitoring 1
• Presoaking root vegetables (e.g., potatoes) can lower potassium content by 50-75% 1

Common Pitfalls to Avoid

1. Failing to verify elevated potassium with a repeat sample to rule out pseudohyperkalemia
2. Not monitoring potassium levels after initiating medications that can cause hyperkalemia
3. Using potassium-containing salt substitutes in patients at risk for hyperkalemia
4. Administering sodium bicarbonate and calcium through the same IV line
5. Not adjusting potassium-raising medications during acute illness or dehydration

Hyperkalemia management requires prompt recognition, appropriate intervention based on severity, and ongoing monitoring to prevent recurrence and associated complications.