Renal, Fluids, Electrolytes & Acid-Base · Topic 12 of 22

Hyperkalemia

Renal & electrolytes · potassium

Hyperkalemia

Get an ECG now. Stabilize the membrane with IV calcium, shift potassium in with insulin and dextrose, then remove it.

Key numbers

Potassium above 5.0 mEq/LK⁺ > 5.0 mEq/L

ECG changes: give IV calcium firstCa gluconate 1 g IV

Insulin 5–10 units IV with dextroseregular insulin 5–10 U IV

01 · Defined byPotassium above 5.0 mEq/L

Normal serum potassium is about 3.5–5.0 mEq/L; hyperkalemia is potassium above the upper limit of normal, > 5.0 mEq/L, from reduced renal excretion or a shift out of cells.

02 · GiveECG changes: give IV calcium first

With ECG changes give 10% calcium gluconate 10–20 mL (1–2 g) IV over 5–10 minutes; it stabilizes the myocardium within minutes for only 20–30 minutes and lowers no potassium. Repeat if the ECG persists.

03 · GiveInsulin 5–10 units IV with dextrose

Shift potassium into cells with regular insulin 5–10 units IV plus 50 mL of 50% dextrose (25 g); the effect peaks in about 1 hour and lasts several hours. Watch glucose for hypoglycemia.

Causes & risk factors

Why it happens

Causes: kidneys, drugs, cell breakdown, acidosisSustained hyperkalemia means reduced renal excretion — AKI, CKD, hypoaldosteronism, or drugs (ACE inhibitors, ARBs, K-sparing diuretics, NSAIDs, trimethoprim, heparin, calcineurin inhibitors) — often plus cell release: rhabdomyolysis, tumor lysis, hemolysis, burns, acidosis, insulin deficiency.

Presentation

What you'll see

Peaked T, then wide QRS, then sine wave must knowECG: peaked T waves, long PR and short QT; above about 6.5 mEq/L the QRS widens and P waves vanish, then a sine wave, VF or asystole. A normal ECG never excludes hyperkalemia.

Diagnosis & monitoring

Work-up

Recheck potassium every 2–4 hoursRecheck potassium every 2–4 hours: shifting agents peak within about 2 hours and wear off by 4, so potassium rebounds unless removed. If it stays above 6 mEq/L, redose and arrange dialysis.

Severity: mild 5.5–5.9, moderate 6.0–6.5, severe > 6.5Common severity grading (European Resuscitation Council, adopted by KDIGO): mild 5.5–5.9, moderate 6.0–6.5, severe > 6.5 mEq/L; any new ECG change raises the severity one level.

Do right now

In this order

First moves

Peaked T, then wide QRS, then sine wave

→

ECG changes: give IV calcium firstCa gluconate 1 g IV

→

Insulin 5–10 units IV with dextroseregular insulin 5–10 U IV

→

Add nebulized albuterol 10–20 mg

→

Remove potassium — hemodialysis if severe or refractory

Why each step

Peaked T, then wide QRS, then sine waveECG: peaked T waves, long PR and short QT; above about 6.5 mEq/L the QRS widens and P waves vanish, then a sine wave, VF or asystole. A normal ECG never excludes hyperkalemia.

ECG changes: give IV calcium firstWith ECG changes give 10% calcium gluconate 10–20 mL (1–2 g) IV over 5–10 minutes; it stabilizes the myocardium within minutes for only 20–30 minutes and lowers no potassium. Repeat if the ECG persists.

Insulin 5–10 units IV with dextroseShift potassium into cells with regular insulin 5–10 units IV plus 50 mL of 50% dextrose (25 g); the effect peaks in about 1 hour and lasts several hours. Watch glucose for hypoglycemia.

Add nebulized albuterol 10–20 mgNebulized albuterol 10–20 mg lowers potassium by about 0.5–1.5 mEq/L as an adjunct to insulin; some patients do not respond. Avoid in unstable angina or acute MI.

Remove potassium — hemodialysis if severe or refractoryCalcium, insulin and albuterol only buy time; start removal early. Hemodialysis is the most effective and is indicated when medical therapy fails, in life-threatening hyperkalemia, and early in kidney failure or end-stage kidney disease.

Management

Orders

Sodium bicarbonate only with metabolic acidosisIV sodium bicarbonate is not a routine shifting agent — evidence is weak; reserve it for concurrent metabolic acidosis. It adds a sodium and volume load and can lower ionized calcium.

Patiromer or SZC to keep RAAS inhibitorsPatiromer (8.4 g daily) and sodium zirconium cyclosilicate (10 g three times daily for up to 48 h) bind gut potassium; too slow for emergencies, they let patients stay on needed RAAS inhibitors.

Mild, no ECG change: stop culprits, diureseFor potassium under 6 mEq/L without ECG changes, stop potassium-raising drugs and supplements, limit intake, add a loop diuretic if the patient is not volume depleted, and consider a binder.

Red flags & don'ts

Avoid harm

Sodium polystyrene sulfonate: slow, risks bowel necrosis avoidSodium polystyrene sulfonate acts slowly and unpredictably, can cause colonic ulceration, ischemia and necrosis, and adds a sodium load; it works poorly with ileus, and enemas are avoided when an acute abdomen is suspected.

True hyperkalemia or pseudohyperkalemia?

Commonly confused

Setting	AKI or CKD, RAAS inhibitors, K-sparing diuretics, tissue breakdown
ECG	May show peaked T waves, wide QRS
Lab clue	None needed
Next step	Treat by severity and ECG

More detail

Reference

Show 6 reference facts

Calcium chloride carries about 3 times the elemental calcium of calcium gluconate and is useful in arrest or instability, but it can cause tissue necrosis if extravasated, so give it through a central line.

Hypoglycemia after insulin–dextrose is common and can occur up to 6 hours later in kidney failure; follow the bolus with D10W at about 50 mL/h and check glucose for several hours.

Calcium was historically contraindicated in digoxin toxicity; Merck still advises caution, but human case series show no harm and the ED consensus calls the contraindication unsupported. Treat digoxin-induced hyperkalemia with digoxin immune Fab.

Insulin and beta-2 agonists drive potassium into cells by stimulating Na⁺/K⁺-ATPase; albuterol's mild hyperglycemia can partly offset insulin-induced hypoglycemia when both are given.

In CKD, hyperkalemia is uncommon until GFR falls below about 10–15 mL/min unless potassium intake is excessive or a potassium-retaining drug is added.

Patiromer binds other oral drugs (e.g. ciprofloxacin, levothyroxine, metformin) — separate dosing by at least 3 hours; separate sodium zirconium cyclosilicate by at least 2 hours.

Pearl

Calcium protects the heart but lowers no potassium; insulin and albuterol only hide it inside cells — the potassium still has to leave the body.

Sources · Merck Manual Professional — Hyperkalemia (reviewed Jun 2025) · Hyperkalemia management in the emergency department: an expert panel consensus. J Am Coll Emerg Physicians Open 2021;2:e12572 · StatPearls — Hyperkalemia (2025; definition confirmed via Europe PMC abstract, PMID 29261936) · Merck Manual Professional — Hypokalemia (lower limit of normal 3.5 mEq/L) · Lindner G et al. Acute hyperkalemia in the emergency department: a summary from a KDIGO Controversies Conference. Eur J Emerg Med 2020;27:329–337 · Starter sheet built from the verified AGACNP fact map (facts reviewed 2026-10-15).