From the Guidelines
Calcium gluconate rapidly reverses the cardiac effects of hyperkalemia by stabilizing the cardiac cell membrane, not by lowering potassium levels. When administered intravenously at a dose of 10 mL of 10% solution (1 gram) over 2-3 minutes, calcium gluconate antagonizes the effect of hyperkalemia on the heart's electrical conduction system, as noted in the management of acute hyperkalemia 1. Hyperkalemia causes cardiac toxicity by decreasing the threshold potential of cardiac cells, which calcium counteracts by increasing this threshold. This stabilizing effect occurs within minutes of administration, specifically within 1 to 3 minutes, and lasts for approximately 30-60 minutes, making it a temporary but life-saving intervention 1.
Key Considerations
- Calcium gluconate should be administered with cardiac monitoring due to potential risks of hypercalcemia.
- While calcium protects the heart, additional treatments such as insulin with glucose, beta-agonists, or dialysis are needed to actually lower serum potassium levels.
- For patients on digoxin, calcium should be administered cautiously as rapid calcium administration can potentiate digoxin toxicity.
Treatment Approach
- Intravenous calcium gluconate administration is a critical step in managing acute hyperkalemia, especially when there are significant ECG changes or severe muscle weakness 1.
- Other treatment options include insulin/glucose, inhaled β-agonists, intravenous sodium bicarbonate, and hemodialysis, which may be used in conjunction with calcium gluconate to manage hyperkalemia effectively 1.
From the Research
Mechanism of Calcium Gluconate in Reversing Hyperkalemia Effects
- Calcium gluconate is used as a cardio-protective therapy in the emergency treatment of severe hyperkalemia 2, 3.
- The beneficial effects of calcium treatment for hyperkalemia have been attributed to "membrane stabilization," however, the underlying mechanisms remain poorly understood 4.
- Calcium gluconate treatment restores conduction through Ca2+-dependent propagation, rather than restoration of membrane potential or "membrane stabilization" 4.
Effectiveness of Calcium Gluconate in Reversing Hyperkalemia Effects
- IV Ca-gluconate therapy was found to be effective, albeit to a limited degree, in main rhythm ECG disorders due to hyperkalemia, but it was not found to be effective in nonrhythm ECG disorders due to hyperkalemia 2.
- Calcium gluconate 10% dosed 10 mL intravenously should be provided for membrane stabilization, unless the patient is in cardiac arrest, in which case 10 mL calcium chloride is warranted 3.
- The combination of nebulised beta agonists with IV insulin-and-glucose was more effective than either alone in treating hyperkalemia, and IV calcium is effective in treating arrhythmia when present 5.
Clinical Considerations
- Hyperkalemia is associated with fatal dysrhythmias and muscular dysfunction, and certain medical conditions can lead to hyperkalemia 6.
- A history and physical examination can be beneficial in the diagnosis of hyperkalemia, and certain characteristic electrocardiogram findings are associated with hyperkalemia along with laboratory potassium levels 6.
- Clinicians must be aware of the different medications available to manage patients with hyperkalemia, including sodium polystyrene sulfonate, sodium zirconium cyclosilicate, and patiromer, each with unique benefits and contraindications 6.