Overview
Hyperkalemia
Quick Reference
Critical Alerts
- Hyperkalemia kills by cardiac arrhythmia: Peaked T waves → Wide QRS → VF/Asystole
- ECG changes require immediate treatment: Calcium gluconate FIRST
- Severe hyperkalemia (>6.5 mEq/L or ECG changes) is an emergency
- Treatment order: Stabilize membrane → Shift K+ → Remove K+
- Pseudohyperkalemia is common: Hemolyzed sample, difficult draw
- Dialysis is definitive for severe or refractory hyperkalemia
ECG Changes (Progressive)
| K+ Level | ECG Finding |
|---|---|
| 5.5-6.5 | Peaked T waves, shortened QT |
| 6.5-7.5 | Prolonged PR, flattened P waves, widened QRS |
| 7.5-8.0 | Wide QRS → Sine wave |
| >.0 | VF, asystole |
Emergency Treatments (In Order)
| Step | Drug | Dose | Mechanism | Onset |
|---|---|---|---|---|
| 1 | Calcium gluconate | 10 mL 10% IV over 2-3 min | Stabilize membrane | Immediate |
| 2 | Insulin + Dextrose | Insulin 10 U IV + D50 25 g | Shift K+ into cells | 15-30 min |
| 3 | Albuterol | 10-20 mg nebulized | Shift K+ into cells | 15-30 min |
| 4 | Sodium bicarbonate | 50 mEq IV | Shift K+ (if acidotic) | 30-60 min |
| 5 | Kayexalate | 15-30 g PO/PR | Remove K+ | Hours |
| 6 | Furosemide | 40-80 mg IV | Remove K+ (if renal function) | Hours |
| 7 | Dialysis | Definitive removal | 1-2 hours |
Definition
Overview
Hyperkalemia is elevated serum potassium (>5.5 mEq/L). Severe hyperkalemia (>6.5 mEq/L) or any level with ECG changes is a medical emergency requiring immediate treatment. The primary life-threatening risk is cardiac arrhythmia. Treatment follows a stepwise approach: membrane stabilization (calcium), intracellular shift (insulin/glucose, albuterol, bicarbonate), and potassium elimination (Kayexalate, diuretics, dialysis).
Classification
By Severity:
| Level | K+ (mEq/L) |
|---|---|
| Mild | 5.5-6.0 |
| Moderate | 6.0-6.5 |
| Severe | >.5 or any ECG changes |
Epidemiology
- Common in hospitalized patients: 1-10%
- Life-threatening arrhythmias: >8 mEq/L
Etiology
Increased Intake:
| Cause | Notes |
|---|---|
| Dietary | Rare unless impaired excretion |
| IV potassium | Iatrogenic |
| Blood transfusion | Stored blood has K+ leak |
Decreased Excretion (Most Common):
| Cause | Notes |
|---|---|
| Acute kidney injury | |
| Chronic kidney disease | |
| Medications | ACE inhibitors, ARBs, K+-sparing diuretics, NSAIDs |
| Hypoaldosteronism | Type IV RTA |
Transcellular Shift (Out of Cells):
| Cause | Notes |
|---|---|
| Acidosis | H+ enters cells, K+ exits |
| Insulin deficiency | DKA |
| Beta-blockers | |
| Rhabdomyolysis | Muscle breakdown |
| Tumor lysis syndrome | Cell lysis |
| Succinylcholine | |
| Digoxin toxicity |
Pseudohyperkalemia:
| Cause | Notes |
|---|---|
| Hemolyzed sample | Common |
| Fist clenching | Venipuncture |
| Leukocytosis/Thrombocytosis | In vitro lysis |
Pathophysiology
Cardiac Effects
- Normal: K+ gradient across cell membrane determines resting potential
- Hyperkalemia: Reduces resting membrane potential → Cells more excitable
- Progressive: Depolarization → Conduction slowing → Arrhythmia
- Severe: VF, asystole
ECG Progression
| Stage | Finding |
|---|---|
| Early | Peaked T waves, shortened QT |
| Progressive | Prolonged PR interval, widened QRS |
| Severe | P wave loss, sine wave pattern |
| Terminal | VF, asystole |
Clinical Presentation
Symptoms
| Symptom | Notes |
|---|---|
| Often asymptomatic | Until severe |
| Muscle weakness | Ascending paralysis in severe cases |
| Paresthesias | |
| Palpitations | |
| Nausea |
History
Key Questions:
Physical Examination
| Finding | Notes |
|---|---|
| Often unremarkable | |
| Muscle weakness | Late |
| Hypotension | If cardiac compromise |
| Arrhythmia |
Known renal disease
Common presentation.
Medications (ACE/ARB, K+-sparing diuretics, NSAIDs)
Common presentation.
Dietary potassium intake
Common presentation.
Muscle trauma (rhabdomyolysis)
Common presentation.
Recent chemotherapy (TLS)
Common presentation.
Diabetes (DKA)
Common presentation.
Previous episodes
Common presentation.
Red Flags
Emergent Treatment Required
| Finding | Concern |
|---|---|
| K+ >.5 mEq/L | Severe hyperkalemia |
| Any ECG changes | Cardiac toxicity |
| Muscle weakness | Severe |
| Cardiac arrest | VF, asystole |
Diagnostic Approach
Laboratory
| Test | Purpose |
|---|---|
| Repeat K+ | Confirm (rule out pseudohyperkalemia) |
| BUN/Creatinine | Renal function |
| Glucose | DKA |
| ABG/VBG | Acidosis |
| Digoxin level | If on digoxin |
| CK | Rhabdomyolysis |
| Uric acid, LDH, phosphorus | TLS |
ECG
- Essential: All patients with suspected hyperkalemia
- Look for peaked T waves, wide QRS, bradycardia
Exclude Pseudohyperkalemia
- Redraw from different site
- Avoid tourniquet/fist clenching
- Send plasma K+ if suspicion high
Treatment
Principles
- Protect the heart: Calcium (stabilize membrane)
- Shift potassium into cells: Insulin/glucose, albuterol, bicarbonate
- Remove potassium from body: Diuretics, Kayexalate, dialysis
Step 1: Membrane Stabilization (Cardiac Protection)
Calcium Gluconate (Or Calcium Chloride via Central Line):
| Agent | Dose | Notes |
|---|---|---|
| Calcium gluconate 10% | 10 mL (1 g) IV over 2-3 min | First-line; repeat in 5 min if no effect |
| Calcium chloride 10% | 5-10 mL IV (central line) | 3× more calcium than gluconate |
Onset: Immediate (1-3 min) Duration: 30-60 min Does NOT lower K+: Only stabilizes membrane
Step 2: Shift Potassium Into Cells
Insulin + Dextrose:
| Agent | Dose | Notes |
|---|---|---|
| Regular insulin | 10 units IV | Combined with dextrose |
| Dextrose 50% | 25-50 g (50-100 mL) IV | Prevent hypoglycemia |
Onset: 15-30 min Duration: 4-6 hours Monitor glucose: Hypoglycemia risk
Albuterol (Nebulized):
| Agent | Dose | Notes |
|---|---|---|
| Albuterol | 10-20 mg nebulized | Synergistic with insulin |
Onset: 15-30 min Caution: Tachycardia; avoid in CAD
Sodium Bicarbonate:
| Agent | Dose | Notes |
|---|---|---|
| Sodium bicarbonate | 50 mEq IV | Only if acidotic (pH under 7.2) |
Onset: 30-60 min Less effective alone: Use with insulin/albuterol
Step 3: Remove Potassium From Body
Diuretics (If Renal Function Allows):
| Agent | Dose |
|---|---|
| Furosemide | 40-80 mg IV |
Onset: Hours Requires urine output
Exchange Resins:
| Agent | Dose | Notes |
|---|---|---|
| Sodium polystyrene sulfonate (Kayexalate) | 15-30 g PO or 30-50 g PR | Slow; risk of bowel necrosis |
| Patiromer | 8.4 g PO | Newer; fewer GI effects |
| Sodium zirconium cyclosilicate (Lokelma) | 10 g PO TID | Faster onset |
Onset: Hours (Kayexalate); faster with newer agents
Dialysis (Definitive):
| Indication | Notes |
|---|---|
| Severe hyperkalemia (>.5) with ECG changes | Definitive removal |
| Refractory to medical therapy | |
| ESRD | No other option |
| Hyperkalemia + Volume overload |
Removes: 50-100 mEq/L per 3-4 hour session
Disposition
Discharge Criteria
- Mild hyperkalemia (5.5-6.0)
- No ECG changes
- Identifiable and reversible cause (e.g., medication)
- Able to follow low-K+ diet
- Close follow-up
Admission Criteria
- K+ >6.0-6.5 mEq/L
- ECG changes
- Symptoms (weakness)
- Renal failure
- Need for dialysis
Referral
| Indication | Referral |
|---|---|
| ESRD/CKD | Nephrology |
| Dialysis | Nephrology |
| Recurrent hyperkalemia | Nephrology, dietitian |
Patient Education
Condition Explanation
- "Your potassium levels are dangerously high, which can affect your heart."
- "We are giving you medications to protect your heart and lower the potassium."
Diet
- Low potassium diet
- Avoid: Bananas, oranges, potatoes, tomatoes, salt substitutes
Medications
- Review and avoid high-K drugs
- Follow-up for renal function
Quality Metrics
Performance Indicators
| Metric | Target | Rationale |
|---|---|---|
| ECG obtained | 100% | Detect cardiac toxicity |
| Calcium given for ECG changes | 100% | Membrane stabilization |
| Insulin + Dextrose given | >5% | Standard treatment |
| Dialysis for severe/refractory | 100% | Definitive |
Documentation Requirements
- K+ level
- ECG interpretation
- Treatment and response
- Cause identified
- Follow-up plan
Key Clinical Pearls
Diagnostic Pearls
- Peaked T waves are earliest ECG change
- Wide QRS is ominous: Impending arrest
- Pseudohyperkalemia is common: Repeat if unexpected
- Check glucose, renal function, acid-base status
- ECG changes may not correlate with K+ level
Treatment Pearls
- Calcium does NOT lower K+: Stabilizes membrane
- Insulin + Dextrose is most reliable for shifting K+
- Albuterol is adjunct, not monotherapy
- Bicarbonate only effective in acidosis
- Kayexalate is slow and risky: Not for emergencies
- Dialysis is definitive: For severe or refractory
Disposition Pearls
- Admit for K+ >6.0 or ECG changes
- ICU for severe hyperkalemia or cardiac instability
- Arrange dialysis if needed
- Medication review essential: Stop offending drugs
References
- Weisberg LS. Management of severe hyperkalemia. Crit Care Med. 2008;36(12):3246-3251.
- Sterns RH, Grieff M, Bernstein PL. Treatment of hyperkalemia: Something old, something new. Kidney Int. 2016;89(3):546-554.
- Kovesdy CP. Updates in hyperkalemia: Outcomes and therapeutic strategies. Rev Endocr Metab Disord. 2017;18(1):41-47.
- Palmer BF. Managing hyperkalemia caused by inhibitors of the renin-angiotensin-aldosterone system. N Engl J Med. 2004;351(6):585-592.
- Clase CM, et al. Potassium homeostasis and management of dyskalemia in kidney diseases. Nat Rev Nephrol. 2020;16(5):285-298.
- KDIGO Clinical Practice Guideline for Acute Kidney Injury. 2012.
- Tintinalli JE, et al. Electrolyte Disorders. Tintinalli's Emergency Medicine. 9th ed. 2020.
- UpToDate. Treatment and prevention of hyperkalemia in adults. 2024.