Hyperkalemia: workup and management
Serum potassium above 5.0 mEq/L. Get an ECG immediately: ECG changes or K ≥6.5 need emergency treatment in three steps: stabilize the membrane, shift K into cells, then remove it.
Working diagnosis
Adult · US guidelines
Draft · awaiting physician review
01Orient
What's new in the evidence
- Consider regular insulin 5 units IV (or 0.1 unit/kg) in patients at high risk of hypoglycemia (ESKD, low pre-treatment glucose, no diabetes); evidence is mixed
- Give dextrose 25–50 g (or follow with a D10 infusion) and check glucose hourly for 4–6 hours
- Sodium polystyrene sulfonate is no longer favored for acute use (bowel necrosis); sodium zirconium cyclosilicate or patiromer are preferred adjuncts
- Binders do not replace calcium, shifting therapy or dialysis in emergencies
Differential diagnoses
- Pseudohyperkalemia (hemolysed sample, high WBC or platelets)
- Acute kidney injury or CKD
- Drugs: ACEi, ARB, MRA, potassium-sparing diuretics, trimethoprim, NSAIDs, heparin, calcineurin inhibitors
- Potassium supplements or salt substitutes
- Cell lysis: rhabdomyolysis, tumor lysis, hemolysis
- Transcellular shift: acidosis, insulin deficiency (DKA), beta-blockers
- Hypoaldosteronism or adrenal insufficiency
02Assess
Risk scores and decision tools
- ECG changes (peaked T, wide QRS, sine wave) trigger calcium regardless of level
- Pre-treatment glucose <125 mg/dL predicts insulin-induced hypoglycemia
- TTKG is no longer recommended; use urine potassium-to-creatinine ratio
Key history questions
- Weakness, palpitations, paresthesia
- Kidney disease, dialysis schedule, missed sessions
- Medication list and recent changes
- Dietary potassium and salt substitutes
- Crush injury, prolonged lie, recent chemotherapy
Examination findings
- Muscle weakness, reduced reflexes
- Bradycardia or irregular rhythm
- Volume status
03Investigate
Initial investigations
- 12-lead ECG: peaked T waves, PR prolongation, flat P, wide QRS, sine wave
- Repeat potassium (non-hemolysed, ideally blood gas)
- BMP, glucose, blood gas for acidosis
- CBC
Advanced investigations
- CK, uric acid, phosphate, LDH if lysis suspected
- Renin, aldosterone and cortisol if no clear cause
04Treat
Immediate management
- ECG changes: calcium gluconate 10% 30 mL (3 g) IV over 5–10 min; repeat if no ECG improvement
- Regular insulin 10 units IV with 25–50 g dextrose; use 5 units (or 0.1 unit/kg) if ESKD, low baseline glucose or no diabetes
- Check glucose hourly for 4–6 hours after insulin
- Nebulized albuterol 10–20 mg as an adjunct
- Continuous cardiac monitoring
First-line treatment
- Stop potassium sources and culprit drugs
- Sodium zirconium cyclosilicate 10 g three times daily for up to 48 hours, or patiromer 8.4 g daily
- Loop diuretic if volume replete and making urine
- Sodium bicarbonate only with metabolic acidosis
Second-line treatment
- Urgent hemodialysis for refractory hyperkalemia, oliguric AKI or ESRD
Specialist referrals
- Nephrology for dialysis or refractory hyperkalemia
- ICU if arrhythmia or hemodynamic compromise
05Disposition
Admission criteria
- K 6.0 or more, or any ECG change
- Ongoing cause (AKI, lysis)
- Needs dialysis
Safe discharge criteria
- Mild hyperkalemia (5.1-5.9) with normal ECG and a correctable cause
- Repeat potassium arranged within 24-72 h
Follow-up timing
- Repeat potassium in 1-3 days after medication changes
Patient instructions
- Low-potassium diet advice
- Avoid salt substitutes and NSAIDs
Monitoring
- Potassium 1-2 h after shifting therapy, then every 2-4 h
- Glucose hourly after insulin
Clinical pearls and pitfalls
- Insulin and albuterol only shift potassium for a few hours; plan removal
- ECG changes correlate poorly with the level, so a normal ECG does not mean safe
RefGuidelines and landmark evidence
For education only. Typical adult starting points; confirm doses against renal function, allergies, interactions and your institution's protocols. Not a substitute for clinical judgment or senior review.