lab valuesintermediate8 min read

Hyperkalemia

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Interactive Diagrams

Potassium Level Ranges

See where potassium levels fall on the clinical spectrum. Tap any zone for details.

2 mEq/LNormal: 3.5–5 mEq/L7.5 mEq/L

Hyperkalemia danger zone

2.5 mEq/L3.5 mEq/L5 mEq/L6 mEq/L

Hyperkalemia Treatment: C-BIG-K-D

The treatment protocol follows a clear priority sequence. Each step has a specific mechanism.

At a Glance

Too much potassium in the blood. Potassium controls how your heart and muscles work electrically. When K+ gets too high, the heart can become dangerously irritable and stop beating properly.

Plain-English Explanation

Potassium is an electrolyte that your cells need to fire electrical signals, especially in the heart and muscles. Normally, most potassium is inside cells and only a small amount is in the blood. The kidneys keep blood potassium levels in a narrow range (3.5-5.0 mEq/L). When the kidneys fail or something floods the blood with extra potassium (crush injury, acidosis, certain medications), the electrical balance gets disrupted. The heart is extremely sensitive to potassium changes — too much K+ slows conduction and can cause the heart to stop.

Must-Know NCLEX Points

Normal K+: 3.5-5.0 mEq/L
Hyperkalemia = K+ > 5.0 mEq/L
Most dangerous effect: cardiac dysrhythmias
ECG changes: tall peaked T waves → widened QRS → sine wave → cardiac arrest
Common causes: renal failure, ACE inhibitors, K+-sparing diuretics, crush injuries, acidosis
Treatment priority: protect the heart first (calcium gluconate)
Insulin + glucose drives K+ back into cells temporarily
Kayexalate (sodium polystyrene sulfonate) removes K+ through the GI tract

Signs and Symptoms

Muscle weakness progressing to flaccid paralysis
Cardiac dysrhythmias (most dangerous)
Tall, peaked T waves on ECG
Nausea, vomiting, diarrhea
Abdominal cramping
Numbness and tingling (paresthesias)
Bradycardia (late finding)
Decreased deep tendon reflexes

Red Flags

K+ > 6.0 mEq/L — medical emergency
Peaked T waves or widened QRS on ECG
Bradycardia or irregular heart rhythm
Ascending muscle weakness or paralysis
Absent deep tendon reflexes

Nursing Interventions

Continuous cardiac monitoring
Administer calcium gluconate IV (protects heart — does NOT lower K+)
Administer regular insulin + D50 glucose IV (shifts K+ into cells temporarily)
Administer sodium bicarbonate if acidotic (shifts K+ into cells)
Administer Kayexalate / sodium polystyrene sulfonate (removes K+ via GI tract)
Restrict potassium in diet
Hold K+-sparing diuretics and ACE inhibitors
Monitor renal function
Prepare for dialysis if severe or refractory
Verify specimen was not hemolyzed (false elevation)

Patient Teaching

Avoid potassium-rich foods when levels are elevated (bananas, oranges, potatoes, tomatoes)
Avoid salt substitutes (many contain potassium chloride)
Know which medications can raise potassium (ACE inhibitors, K+-sparing diuretics)
Report muscle weakness, tingling, or palpitations promptly
Keep follow-up appointments for lab monitoring

Memory Aid

MURDER for Hyperkalemia symptoms: M — Muscle weakness U — Urine output decreased (renal cause) R — Respiratory failure (if severe) D — Decreased cardiac contractility E — ECG changes (peaked T waves) R — Reflexes decreased Treatment order: "C-BIG-K-D" C — Calcium gluconate (protect heart) B — Bicarbonate (if acidotic) I — Insulin (with) G — Glucose (shift K+ into cells) K — Kayexalate (remove K+ from body) D — Dialysis (if refractory)

NCLEX Strategy

NCLEX frequently asks about ECG changes with hyperkalemia — peaked T waves is the classic answer. Know the treatment priority: calcium gluconate first (stabilizes the heart), then insulin/glucose (shifts K+ into cells). Remember calcium gluconate does NOT lower potassium — it only protects the heart while other treatments work. Questions about ACE inhibitors and K+-sparing diuretics often involve hyperkalemia as a side effect. If a question asks "which patient is at highest risk for hyperkalemia?" look for renal failure.

Quick Check

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