Renal, Fluids, Electrolytes & Acid-Base · Topic 13 of 23

Hyperkalemia

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Renal & electrolytes · potassium

Hyperkalemia

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

01 · Defined bySerum K⁺ over 5.0 mEq/L

02 · ECG changesCalcium gluconate 1–2 g IV first

03 · Then shiftInsulin 5–10 units IV with 25 g dextrose

What causes it

Sustained hyperkalemia means reduced renal excretion, often plus cell release

Reduced excretion

AKICKDHypoaldosteronism

Drugs

ACE inhibitorsARBsK-sparing diureticsNSAIDsTrimethoprimHeparinCalcineurin inhibitors

Release from cells

RhabdomyolysisTumor lysisHemolysisBurnsAcidosisInsulin deficiency

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

What you'll see: the ECG

Peaked T, then wide QRS, then sine wave — a normal ECG never excludes it

Peaked T waves, long PR, short QT early

Over ~6.5 mEq/L: wide QRS, P waves vanish late

Sine wave, VF or asystole arrest

Why shifting only buys time

Shifting hides potassium inside cells — removal still has to follow

Insulin and albuterol move K⁺ into cells via Na⁺/K⁺-ATPase; none leaves the body

Diagnosis & severity

Grade it, then make sure it's real

Normal K⁺ 3.5–5.0 · hyperkalemia over 5.0 mEq/L

Mild 5.5–5.9 · moderate 6.0–6.5 · severe over 6.5 mEq/L

Any new ECG change raises severity one level

No risk factors, normal ECG: suspect pseudohyperkalemia

Hemolysis, tourniquet, fist clenching, high platelets or WBC

Pseudohyperkalemia: repeat a careful draw, processed promptly

No universal cutoff: StatPearls gives over 5.0–5.5; Merck and the ED consensus define hyperkalemia as over 5.5 mEq/L. Heart failure rules start an MRA at K⁺ under 5.0 and stop it over 5.5. Severity grading is the European Resuscitation Council's, adopted by KDIGO.

Red flags

Any ECG change from hyperkalemia IV calcium

ECG changes persist after calcium repeat calcium

K⁺ still over 6 on recheck (every 2–4 h) redose, dialyze

Life-threatening or refractory to medical therapy hemodialysis

Albuterol in unstable angina or acute MI avoid albuterol

Hypoglycemia after insulin and dextrose check glucose

Shifting agents peak within about 2 hours and wear off by 4, so potassium rebounds unless removed.

Treatment

Stabilize, shift, then remove — the first two only buy time

First moves, in order

12-lead ECG nowa normal ECG doesn't exclude hyperkalemia

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ECG changes: calcium gluconate 1–2 g IVover 5–10 min · repeat if changes persist

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Insulin 5–10 units IV + dextrose 25 gpeaks in about 1 h · watch glucose

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Add nebulized albuterol 10–20 mgadjunct · some patients don't respond

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Start removal earlyhemodialysis if life-threatening or refractory

Stabilizeprotect the heart

Calcium gluconate 10% 10–20 mL IV

Stabilizes the myocardium in minutes — lowers no K⁺

Lasts only 20–30 minutes

Shiftinto cells

Regular insulin 5–10 units IV Dextrose 50% 50 mL (25 g) Albuterol 10–20 mg nebulized

Insulin with dextrose, plus albuterol as an adjunct

Albuterol lowers K⁺ about 0.5–1.5 mEq/L

Bicarbonateacidosis only

Sodium bicarbonate IV

Only with concurrent metabolic acidosis — not routine

Sodium and volume load; can lower ionized calcium

Removethe real fix

Hemodialysis is the most effective removal

Early in kidney failure or end-stage kidney disease

Binderskeep RAAS drugs

Patiromer 8.4 g daily SZC 10 g TID for up to 48 h

Let patients stay on needed RAAS inhibitors

Too slow for emergencies

Polystyreneavoid if able

Sodium polystyrene sulfonate

Slow, unpredictable; colonic ischemia and necrosis

Works poorly with ileus; no enema if acute abdomen suspected

Mildunder 6, no ECG change

Loop diuretic

Stop K⁺-raising drugs and supplements, limit intake

Loop diuretic if not volume depleted; consider a binder

Calcium chloride, glucose, digoxin, binders

Calcium chloride: ~3× the elemental calcium of gluconateuseful in arrest or instability; give centrally — extravasation causes necrosis

Hypoglycemia can occur up to 6 h later in kidney failurefollow the bolus with D10W at about 50 mL/h; check glucose for several hours

Digoxin toxicity: calcium was historically contraindicatedMerck advises caution; case series show no harm; treat with digoxin immune Fab

Albuterol's mild hyperglycemia may ease insulin-induced hypoglycemia

Separate other oral drugs: patiromer ≥ 3 h, SZC ≥ 2 hpatiromer binds ciprofloxacin, levothyroxine, metformin

KDIGO ED summary: 30 mL of 10% gluconate ≈ 10 mL of 10% chloride (about 3 times the calcium per mL). Merck: gluconate 5–10 mL over 2 min for sine wave or asystole. Some protocols use 5 units of insulin to lower hypoglycemia risk in kidney failure; 10 units lowers K⁺ as well as 20, with less hypoglycemia.

True hyperkalemia or pseudohyperkalemia?

	True hyperkalemia	Pseudohyperkalemia
Setting	AKI or CKD, RAAS inhibitors, K-sparing diuretics, tissue breakdown	No risk factors
ECG	May show peaked T waves, wide QRS	Normal
Lab clue	None needed	Hemolysis, tourniquet or fist clenching, very high platelets or WBC
Next step	Treat by severity and ECG	Repeat a careful draw, processed promptly

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 · Hyperkalemia (Merck Manual Professional, 2025) · Hyperkalemia management in the emergency department: expert panel consensus (JACEP Open 2021) · Hyperkalemia (StatPearls, 2025) · Hypokalemia (Merck Manual Professional) · Acute hyperkalemia in the ED: KDIGO Controversies Conference summary (Eur J Emerg Med 2020) · Follow your institution's protocols.