In an adult with severe hyperkalemia (serum potassium ≥6.0 mmol/L) or ECG changes, how should insulin be administered—including dose, glucose co‑administration, monitoring, and special considerations?

Role of Insulin in Hyperkalemia Treatment

For severe hyperkalemia (≥6.0 mmol/L) or ECG changes, administer 10 units of regular insulin IV push with 25 grams of dextrose (50 mL D50W) to shift potassium intracellularly, with onset in 15–30 minutes and duration of 4–6 hours. 1

Mechanism and Efficacy

Insulin drives potassium from the extracellular space into cells by activating the Na⁺-K⁺-ATPase pump, producing a mean serum potassium reduction of 0.5–1.2 mEq/L within 30–60 minutes. 1, 2 This transcellular shift is temporary—it does not remove potassium from the body—so definitive elimination strategies (diuretics, dialysis, or potassium binders) must be initiated concurrently. 1, 3

Insulin is the most reliable agent for promoting intracellular potassium shift in acute hyperkalemia. 3 The effect peaks at 30–60 minutes and persists for 4–6 hours, after which rebound hyperkalemia may occur if the underlying cause is not addressed. 1, 2

Dosing Protocols

Standard Dose (10 Units)

• 10 units regular insulin IV push with 25 grams dextrose (50 mL D50W) is the established regimen for most patients with severe hyperkalemia. 1, 4
• This dose produces consistent potassium lowering across multiple studies, with a mean reduction of 0.78 ± 0.25 mmol/L at 60 minutes. 4

Reduced Dose (5 Units or 0.1 Units/kg)

• 5 units regular insulin or 0.1 units/kg may be considered to reduce hypoglycemia risk, particularly in patients with low baseline glucose, no diabetes, female sex, or renal impairment. 2
• However, reduced-dose insulin is less effective when baseline potassium exceeds 6.0 mmol/L, producing a significantly smaller potassium reduction (−0.238 mmol/L difference, P = 0.018). 5
• For severe hyperkalemia (K⁺ >6.5 mmol/L) or marked ECG changes, use the standard 10-unit dose to ensure adequate potassium lowering. 4

High-Dose Infusion (20 Units)

• 20 units regular insulin as a continuous IV infusion over 60 minutes may be used in patients with severe hyperkalemia (K⁺ >6.5 mmol/L) or marked ECG changes (prolonged PR, widened QRS). 4
• This regimen produces a mean potassium reduction of 0.79 ± 0.25 mmol/L at 60 minutes, statistically equivalent to the 10-unit bolus. 4
• When using 20 units, administer 60 grams of dextrose (instead of 25 grams) to prevent hypoglycemia. 4

Glucose Co-Administration

Glucose must always accompany insulin to prevent life-threatening hypoglycemia. 1, 6 The standard regimen pairs 10 units insulin with 25 grams dextrose, but hypoglycemia remains a frequent complication, occurring in approximately 20% of patients. 4

Strategies to Reduce Hypoglycemia Risk

• Increase dextrose to 50 grams (100 mL D50W) instead of 25 grams when using 10 units insulin. 2
• Administer dextrose as a prolonged infusion (e.g., D10W at 100 mL/hr) rather than a rapid bolus, extending glucose availability beyond insulin's duration of action. 2
• Use 60 grams dextrose when administering 20 units insulin. 4

High-Risk Populations for Hypoglycemia

• Low baseline glucose (<100 mg/dL) 2
• No history of diabetes mellitus 2
• Female sex 2
• Impaired renal function (eGFR <30 mL/min) 2
• Lower body weight 2

Monitoring Requirements

Glucose Monitoring

• Check blood glucose hourly for at least 4–6 hours after insulin administration, as insulin's duration of action may exceed that of dextrose. 2
• Patients with renal impairment or low baseline glucose require more frequent monitoring. 2

Potassium Monitoring

• Recheck serum potassium 1–2 hours after insulin/glucose administration to confirm adequate response. 1
• Continue monitoring every 2–4 hours during the acute treatment phase until potassium stabilizes. 1
• Rebound hyperkalemia is common after 4–6 hours as the insulin effect wanes, particularly in patients with ongoing potassium release (tumor lysis syndrome, rhabdomyolysis) or impaired renal excretion. 1

ECG Monitoring

• Obtain a repeat ECG after treatment to document resolution of hyperkalemic changes (peaked T waves, widened QRS, prolonged PR). 1
• Continuous cardiac monitoring is mandatory for severe hyperkalemia (K⁺ >6.5 mmol/L) or any ECG changes. 1

Special Considerations

Diabetic Ketoacidosis (DKA)

• Delay insulin therapy if K⁺ <3.3 mEq/L in DKA patients, as insulin will further lower potassium and provoke life-threatening arrhythmias. 7
• Once K⁺ falls below 5.5 mEq/L with adequate urine output, add 20–30 mEq potassium to each liter of IV fluid (2/3 KCl and 1/3 KPO₄). 7

Renal Failure

• Insulin remains effective in renal failure, but hypoglycemia risk is increased due to reduced insulin clearance. 2
• Hemodialysis is the most reliable method for potassium removal in severe hyperkalemia with renal failure and should be initiated promptly. 1, 3

Combination Therapy

• Nebulized albuterol (10–20 mg in 4 mL) augments insulin's effect, providing an additional 0.5–1.0 mEq/L potassium reduction within 30 minutes. 1, 3
• The combined insulin-glucose plus beta-agonist regimen is more effective than either modality alone. 1

Critical Pitfalls to Avoid

• Never administer insulin without glucose—hypoglycemia can be fatal. 1
• Do not use reduced-dose insulin (5 units) when K⁺ >6.0 mmol/L or ECG changes are present—the standard 10-unit dose is required for adequate potassium lowering. 5, 4
• Do not assume a single dose is sufficient—insulin is a temporizing measure that does not remove potassium from the body; definitive elimination strategies must be initiated. 1, 3
• Do not stop glucose monitoring after 1–2 hours—hypoglycemia can occur 4–6 hours post-administration as insulin's effect outlasts dextrose. 2
• Do not forget to address the underlying cause—rebound hyperkalemia is common if contributing factors (medications, renal failure, ongoing potassium release) are not corrected. 1, 6