USMLE Prep - Medical Reference Library

Hyperkalemia — ECG Risks & Treatment Algorithm

System: Nephrology • Reviewed: Aug 31, 2025 • Step 1Step 2Step 3

Synopsis:

Immediate threat when ECG changes or K+ ≥6.0. Stabilize membrane, shift K+ intracellularly, and remove K+; address causes and prevent recurrence.

Key Points

  • Stabilize ABCs; begin targeted evaluation without delaying life-saving therapy.
  • Use system-specific risk tools to guide testing and disposition.
  • Order high-yield tests first; escalate imaging when indicated.
  • Start evidence-based initial therapy and reassess frequently.

Algorithm

  1. Primary survey and vitals; IV access and monitors.
  2. Focused history/physical; identify red flags and likely etiologies.
  3. Order system-appropriate labs and imaging (see Investigations).
  4. Initiate guideline-based empiric therapy (see Pharmacology).
  5. Reassess response; arrange consultation and definitive management.

Clinical Synopsis & Reasoning

Hyperkalemia threatens membrane excitability and cardiac conduction; verify with repeat lab and evaluate for hemolysis. Assess ECG for peaked T waves, QRS widening, and sine‑wave morphology; identify precipitants such as renal failure, tissue breakdown, and RAAS‑inhibiting drugs.


Treatment Strategy & Disposition

Stabilize myocardium with IV calcium for ECG changes, shift K⁺ intracellularly with insulin–dextrose and β‑agonists, and enhance elimination via loop diuretics, potassium binders, or dialysis when appropriate. Address causative agents and correct metabolic acidosis. Admit for ECG changes, ongoing tissue breakdown, or need for continuous monitoring; otherwise arrange timely outpatient follow‑up and medication reconciliation.


Management Notes

Beware rebound hyperkalemia after shifts; consider long‑term binders for chronic management.


Epidemiology / Risk Factors

  • CKD/AKI, nephrotoxins; obstruction

Investigations

TestRole / RationaleTypical FindingsNotes
BMPRenal/electrolytesAKI/lyte changes
UA ± cultureHematuria/proteinuria/infectionFindings vary
Renal ultrasound (selected)ObstructionHydronephrosis

Emergency Therapies

ActionDose/Notes
Calcium gluconate1–2 g IV; repeat if ECG unchanged
Regular insulin + dextrose10 U IV + 25 g dextrose; repeat glucose checks
Nebulized albuterol10–20 mg
Sodium bicarbonateIf acidemic
DialysisDefinitive in ESRD or refractory cases

Pharmacology

MedicationMechanismOnsetRole in TherapyLimitations
Calcium gluconate (IV)Myocardial membrane stabilizationMinutesECG changes or K ≥6.5Extravasation risk
Insulin + dextroseCellular K⁺ shiftMinutesTemporizingHypoglycemia
Albuterol (neb)β2-agonistMinutesAdjunct shiftTachycardia
Loop diuretic / dialysisK⁺ removalHoursDefinitive removalVolume depletion / access
Sodium bicarbonate (IV)Buffers acidosisMinutesIf severe acidemiaVolume/Na load

Prognosis / Complications

  • Reversibility by cause; electrolyte/volume complications

Patient Education / Counseling

  • Explain red flags and when to seek emergent care.
  • Reinforce medication adherence and follow-up plan.

References

  1. KDIGO/EM Guidelines — Hyperkalemia — Link