Quick Recap
Renal System, Protocol 4/7.
1. Definition & Mechanisms
Three primary mechanisms (per the Washington Manual framework): (a) transcellular shifts, (b) reduced glomerular filtration, (c) effective aldosterone deficiency. Sustained hyperkalemia almost ALWAYS requires decreased renal function — normal kidneys have tremendous K+ excretion capacity, so persistent hyperkalemia in a patient with normal renal function should prompt reconsidering the diagnosis (pseudohyperkalemia) or looking for an aldosterone-axis problem.
UK+/UCr >200 mEq K+/g creatinine is the expected renal response to hyperkalemia; values below this suggest a defect in renal excretion as a contributing mechanism.
2. Causes (Organized by Mechanism)
Category | Examples |
Increased release from cells | Pseudohyperkalemia (hemolyzed sample, marked leukocytosis/thrombocytosis, vigorous fist clenching during phlebotomy — suspect when NO ECG changes despite moderate-severe reported hyperkalemia); metabolic acidosis; insulin deficiency/hyperglycemia/hyperosmolality (DKA, HHS, octreotide infusion); tissue catabolism; beta-blockade; rhabdomyolysis; digitalis overdose; hyperkalemic periodic paralysis; succinylcholine; tumor lysis syndrome; severe exercise |
Reduced urinary excretion | Renal failure; hypoaldosteronism (spironolactone, eplerenone, propranolol, labetalol, ARB, ACE-I, NSAIDs, diabetes, adrenal insufficiency); type 4 (hyperkalemic) RTA; ureterojejunostomy |
Increased intake | Oral/IV potassium, especially with concurrent renal impairment |
Transcellular shift causes of special ICU importance: insulin deficiency, ECF hyperosmolality, inorganic acidemia, and cell breakdown (rhabdomyolysis, hemolysis, tumor lysis syndrome) — these shift K+ from ICF to ECF WITHOUT changing total body K+ content, and often AMPLIFY hyperkalemia from other concurrent causes.
3. Immediate Stabilization (ABCDE)
Circulation — the entire focus of this protocol:
- Urgent IV access and continuous ECG monitoring for severe hyperkalemia
- Can cause sudden bradycardic arrest — follow ACLS if this occurs
- In cardiac arrest with suspected hyperkalemia: give IV calcium gluconate/chloride IMMEDIATELY, even before potassium results are available — do not wait for lab confirmation in this specific emergency scenario
- AVOID succinylcholine during RSI in suspected hyperkalemia (can precipitate further dangerous potassium release, especially with denervation states — see the same principle in the GBS protocol, Neurology System)
- AVOID potassium-containing resuscitation fluids (lactated Ringer's, other balanced salt solutions) during active hyperkalemia resuscitation — though note the AKI protocol's point that balanced solutions' potassium content (~4 mEq) is LOW and the acidifying effect of saline may actually worsen hyperkalemia more than balanced solution's potassium content; use clinical judgment on this nuanced tradeoff rather than reflexively avoiding all balanced solutions
Checklist:
4. Severity/Urgency Assessment — When to Treat Urgently
Urgent management indicated for: ECG changes (though progression/severity of ECG changes does NOT always correlate well with serum potassium level — treat based on the ECG picture and clinical context, not a rigid potassium-to-ECG-stage mapping); muscle weakness/paralysis; rhabdomyolysis; crush injury; tumor lysis syndrome; serum K+ >7.0 mEq/L; OR rapidly rising K+ above 5 mEq/L (rate of rise matters as much as absolute level).
ECG progression (roughly sequential, though individual variability exists):
- Tall, peaked T waves with shortened QT interval
- Progressive PR interval lengthening and QRS widening
- Disappearance of P waves
- Further QRS widening merging with T wave -> sine wave pattern
- Ventricular fibrillation, asystole
(Also: right/left bundle branch block, bifascicular block, advanced AV block can occur at various points)
5. Acute Treatment — Full Dosing Table
Treatment | Dosing | Onset/Duration | [K+] decline | Key notes |
Calcium gluconate/chloride | 1g (10mL of 10%) IV over 2-3 min; repeat if no ECG improvement by 5 min | Immediate, lasts 30-60 min | NONE — does not lower K+ | Stabilizes cardiac membrane only; calcium chloride has 3x the elemental calcium of gluconate (13.6 vs 4.6 mEq per 10mL of 10%) and is preferred where central access available; give calcium chloride via CENTRAL vein to avoid extravasation/skin necrosis; do NOT mix with bicarbonate-containing solutions (precipitation risk); use cautiously/slow infusion in patients on digitalis |
Insulin + dextrose | 10 units regular insulin IV + 50mL D50 (omit dextrose if glucose already >250) | Onset 10-15 min, lasts 4-8h | ~0.5-1.2 mEq/L (~1 mEq/L) | Monitor glucose q30min; watch for hypo- AND hyperglycemia (the latter can offset the K+-lowering effect); beware hypoglycemia especially in renal failure |
Albuterol (nebulized or IV) | 10-20mg nebulized over 15 min (4x usual bronchodilator dose) OR 0.5mg IV in 100mL D5W over 15 min | Onset 10-30 min, lasts 3-6h | 0.5-1.5 mEq/L | Tachycardia and variable BP effects; hyperglycemia may offset some K+-lowering effect; works by driving K+ intracellularly, same mechanism as insulin — additive when combined |
Sodium bicarbonate | 2-4 mEq/min drip, or 25-50 mEq bolus over 5 min in select cases | Onset ~4h, lasts >6h | 0.5-0.75 mEq/L | Has FALLEN OUT OF FAVOR given comparatively weak effect UNLESS a concurrent inorganic metabolic acidosis is present — do not rely on bicarbonate as a primary hyperkalemia therapy absent acidosis; watch for volume overload and can LOWER ionized calcium (increasing arrhythmia susceptibility) |
Loop +/- thiazide diuretics | Widely variable, GFR-dependent | Variable | Variable | Promotes renal excretion; requires adequate residual renal function |
Sodium zirconium cyclosilicate (Lokelma) | 10g up to 3x daily | Slower onset | — | Newer cation exchanger; promotes GI potassium excretion; comparative RCT data exists vs older exchangers |
Hemodialysis | — | — | Removes 25-50 mEq K+/hour | Variable based on initial K+, dialyzer type/surface area, blood/dialysate flow rate, duration, dialysate K+ concentration; watch for REBOUND hyperkalemia after dialysis completes (intracellular-to-extracellular re-equilibration) |
Critical conceptual framework: calcium STABILIZES the membrane (immediate, no K+ change); insulin/albuterol SHIFT potassium intracellularly (temporary, doesn't remove total body K+); diuretics/exchangers/dialysis EXCRETE/REMOVE potassium (the only therapies that address total body K+ burden). All three categories are typically needed together for significant hyperkalemia — shift therapies buy time while excretion/removal therapies work.
Sodium polystyrene sulfonate (Kayexalate) caution: historically used, but associated with intestinal necrosis, particularly when combined with sorbitol — use with caution, especially in post-operative or bowel-compromised patients; newer agents (sodium zirconium cyclosilicate, patiromer) are increasingly preferred where available given this safety concern.
6. Investigations
Repeat/confirm serum potassium (rule out pseudohyperkalemia if unexpected), BUN/creatinine, sodium/calcium/magnesium/phosphate, ABG, CBC (leukocytosis/thrombocytosis as pseudohyperkalemia clues), glucose, CPK (rhabdomyolysis), LDH (hemolysis/tumor lysis), medication review (ACE-I/ARB/NSAID/potassium-sparing diuretic/potassium supplements). Urinary potassium excretion and TTKG (transtubular potassium gradient) have LIMITED utility in determining hyperkalemia cause despite historical teaching — do not over-rely on these calculations clinically.
7. Underlying Cause Management
Stop all potassium intake (potassium-free diet, discontinue potassium-containing medications/drugs that impair excretion). Address the specific etiology once identified (renal failure -> RRT per indications; adrenal insufficiency -> steroid replacement; medication-induced -> discontinue offending agent).
8. Organ Support
Hemodialysis for severe/refractory hyperkalemia (see CRRT Indications and Dialysis Emergencies protocols); standard ICU supportive care; continuous cardiac monitoring throughout treatment.
9. Consultation Matrix
Consultation | Trigger | Timing |
Nephrology | Severe/refractory hyperkalemia, RRT need | Immediate for K+ >6.5 or ECG changes |
Cardiology | Refractory arrhythmia despite standard therapy | As needed |
Endocrinology | Suspected adrenal insufficiency/hypoaldosteronism as underlying cause | As needed |
10. Monitoring Framework
Continuous ECG during acute treatment, serum potassium rechecked frequently (e.g., 1-2h post-treatment, then per trend), glucose monitoring during insulin therapy (q30min initially), watch for rebound hyperkalemia post-dialysis, ionized calcium if bicarbonate used.
11. Complications
Arrhythmia/cardiac arrest (the primary feared complication), hypoglycemia from insulin therapy, calcium extravasation/tissue necrosis (esp. calcium chloride via peripheral line), volume overload/hypocalcemia from bicarbonate, intestinal necrosis (sodium polystyrene sulfonate + sorbitol), rebound hyperkalemia post-dialysis. Prevention: appropriate calcium administration route (central for chloride), glucose monitoring with insulin, avoiding bicarbonate absent concurrent acidosis, cautious use of older exchange resins. Rescue: repeat calcium for persistent ECG changes, escalation to dialysis for refractory cases, ACLS for arrest.
12. Escalation & De-escalation
Escalate: ECG changes not resolving with calcium, K+ >6.5-7.0 or rapidly rising, refractory to shift therapies -> hemodialysis.
De-escalate: K+ normalized, ECG normalized, underlying cause addressed -> discontinue potassium-restriction diet as appropriate, resume necessary medications cautiously with monitoring, transition to outpatient/ward-level surveillance.
13. ICU Discharge Criteria
Potassium normalized and stable, no ongoing ECG changes, underlying cause identified and addressed (or dialysis-dependent status established with outpatient plan), medication reconciliation completed to prevent recurrence.
14. Documentation & Medicolegal Checklist
15. Key Guidelines
Palaka E, et al. Evidence in support of hyperkalaemia management strategies: a systematic literature review. Int J Clin Pract. 2018;72(2) — comprehensive comparative evidence review including newer agents (sodium zirconium cyclosilicate) vs established therapies.
16. Controversies
The magnitude and reliability of sodium bicarbonate's potassium-lowering effect absent concurrent metabolic acidosis remains debated — current consensus favors de-emphasizing it as primary therapy, but practice variation persists. Optimal threshold for choosing newer cation exchangers (sodium zirconium cyclosilicate, patiromer) over traditional sodium polystyrene sulfonate involves cost/availability tradeoffs against the established (if debated) intestinal necrosis risk of the older agent. TTKG's clinical utility, despite historical teaching, is now considered limited — a good example of evolving practice away from an older diagnostic tool.
17. References
- Sterns RH, Emmett M. Disorders of Plasma Sodium, Potassium, Calcium, Magnesium, and Phosphorus (hyperkalemia section). Washington Manual of Critical Care, 4th ed, 2025 (Ch. 26).
- Todi S, Chawla R. Hypokalemia and Hyperkalemia. ICU Protocols: A Step-wise Approach, 2nd ed. Springer; 2020 (Ch. 3).
- Palaka E, Grandy S, Darlington O, McEwan P, van Doornewaard A. Evidence in support of hyperkalaemia management strategies: a systematic literature review. Int J Clin Pract. 2018;72(2).
- Effa E, et al. Pharmacological interventions for the management of acute hyperkalaemia in adults. Nephrology (Carlton). 2017;22(1):5-6.
- McGowan CE, Saha S, Chu G, et al. Intestinal necrosis due to sodium polystyrene sulfonate (Kayexalate) in sorbitol. South Med J. 2009;102:493.
See also: Acute Kidney Injury and CRRT Indications (Renal System) for dialysis-based potassium removal; Rhabdomyolysis and Tumor Lysis Syndrome (Renal System, forthcoming) for the specific transcellular-shift-driven hyperkalemia these conditions cause.