Hyperkalemia: ECG Changes and Treatment Order

Medical-Surgical · Renal & Genitourinary·Updated 2026-10-28

What it is

Hyperkalemia is a serum potassium above 5.0 mEq/L (5.0 mmol/L). Potassium sets the resting membrane potential, so a high level makes cardiac and skeletal muscle cells unstable, causing dysrhythmias and muscle weakness. The main causes are kidney failure, drugs that retain potassium (ACE inhibitors, ARBs, spironolactone), excess intake including salt substitutes, cell destruction (crush injury, burns, tumor lysis), and acidosis or insulin deficiency, which shift potassium out of cells.

What the NCLEX focuses on

ECG progression: tall peaked T waves, then prolonged PR interval, flattened or absent P waves, widened QRS, sine wave pattern, and ventricular fibrillation or asystole.
Neuromuscular and GI signs: paresthesias, muscle weakness progressing to flaccid paralysis, abdominal cramping and diarrhea.
A high result in an asymptomatic client after a difficult draw suggests a hemolyzed sample: obtain an ECG and redraw promptly.
IV calcium gluconate stabilizes the cardiac membrane within minutes but does not lower serum potassium.
IV regular insulin with dextrose and nebulized albuterol shift potassium into cells; insulin keeps acting after the potassium falls, so hypoglycemia follows.
Potassium is removed by potassium binders (sodium zirconium cyclosilicate, patiromer, sodium polystyrene sulfonate), loop diuretics if the kidneys respond, and hemodialysis, the definitive treatment in kidney failure.
Hold and clarify potassium sources: supplements, salt substitutes, spironolactone, ACE inhibitors, ARBs, NSAIDs and IV fluids containing potassium.

Priority nursing actions

Assess the client, place on a continuous cardiac monitor and obtain a 12-lead ECG.
Give IV calcium gluconate as prescribed when ECG changes are present.
Give IV regular insulin with dextrose (and albuterol if prescribed) to shift potassium into cells.
Remove potassium with the prescribed binder or loop diuretic, or prepare for emergency hemodialysis.
Stop all potassium sources and recheck potassium and blood glucose as prescribed.

Numbers to know

Value	Normal or target	Why it matters
Potassium	3.5 to 5.0 mEq/L (3.5 to 5.0 mmol/L)	Above 5.0 is hyperkalemia
Emergency level	Above 6.0 mEq/L (6.0 mmol/L) or any ECG change	Cardiac monitor and immediate treatment
Calcium gluconate onset	Within minutes; lasts 30 to 60 minutes	Buys time; potassium still needs removal
Insulin with dextrose	10 units regular insulin IV with 25 g dextrose	Lowers potassium within 15 to 30 minutes
Blood glucose after insulin	Recheck hourly for several hours	Detects delayed hypoglycemia

Common exam traps

Choosing insulin with dextrose before calcium gluconate when the ECG shows changes: wrong because calcium protects the heart from a lethal dysrhythmia first.
Choosing to believe the potassium is corrected after calcium gluconate: wrong because calcium does not lower potassium.
Choosing emergency treatment for a likely hemolyzed result in an asymptomatic client before an ECG and redraw: wrong because the result needs confirmation first.
Choosing a salt substitute to lower sodium intake in CKD: wrong because most contain potassium chloride.
Choosing to stop glucose checks once the potassium falls: wrong because shakiness and sweating an hour later signal insulin-induced hypoglycemia.

What to teach

Limit high-potassium foods (bananas, oranges and orange juice, potatoes, tomatoes, dried fruit, avocados, spinach) as prescribed.
Avoid salt substitutes, potassium supplements and NSAIDs unless the provider approves.
Keep laboratory appointments when taking ACE inhibitors, ARBs or spironolactone.
Report muscle weakness, palpitations or an irregular heartbeat right away.

Client handout: Chronic Kidney Disease: Food and Fluids (nurse guide and printable patient handout).

Try 2 NCLEX-style questions on this topic

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Question 1 · QID DF8FC656

A client has a potassium level of 7.0 mEq/L and peaked T waves. Which prescription should the nurse implement first?

Select the best answer.

A. IV regular insulin with dextrose
B. IV calcium gluconate
C. Nebulized albuterol treatment
D. IV sodium bicarbonate administration

Question 2 · QID EC7556C2

A client with CKD has potassium 6.2 mEq/L. Which items on the current orders should the nurse hold and clarify? Select all that apply.

A. Spironolactone daily
B. Lisinopril daily
C. Salt substitute with meals
D. Insulin glargine at bedtime
E. IV 0.9% sodium chloride
F. Ibuprofen as needed

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Acute PancreatitisRecognize acute pancreatitis by pain and lipase, give fluids and pain control first, and catch hypocalcemia, shock and respiratory failure.Bowel Obstruction and NG Tube CareTell small from large bowel obstruction, spot strangulation early, and keep a decompression NG tube placed, patent and safe.Acute Kidney Injury vs Chronic Kidney DiseaseClassify AKI as prerenal, intrarenal or postrenal, follow its phases, and compare it with the staged, irreversible course of CKD.

Sources

Harding MM, Kwong J, Hagler D, Reinisch C. Lewis's Medical-Surgical Nursing: Assessment and Management of Clinical Problems. 12th ed. Elsevier; 2023; Chapter: Fluid, Electrolyte, and Acid-Base Imbalances.
Harding MM, Kwong J, Hagler D, Reinisch C. Lewis's Medical-Surgical Nursing: Assessment and Management of Clinical Problems. 12th ed. Elsevier; 2023; Chapter: Acute Kidney Injury and Chronic Kidney Disease.
Potter PA, Perry AG, Stockert PA, Hall AM. Fundamentals of Nursing. 10th ed. Elsevier; 2021.

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