From the Guidelines
Sodium bicarbonate should only be used in hyperkalemia to promote potassium elimination through increased urinary potassium excretion in patients with concurrent metabolic acidosis, as stated in the 2021 study published in the Mayo Clinic Proceedings 1. The purpose of bicarbonate in hyperkalemia is to help eliminate potassium from the body by increasing urinary potassium excretion, which is particularly useful in patients with metabolic acidosis.
- The effect of bicarbonate is most beneficial in patients with acidosis, as it helps to decrease blood acidity and promote potassium excretion through increased distal sodium delivery, as noted in the 2021 study published in the Mayo Clinic Proceedings 1.
- However, bicarbonate therapy alone is insufficient for managing hyperkalemia and should be used alongside other treatments such as insulin with glucose, beta-agonists, calcium, and potassium-binding resins or dialysis when appropriate.
- The use of sodium bicarbonate in hyperkalemia is limited to patients with metabolic acidosis, and its effectiveness in patients without acidosis is less predictable, as stated in the 2021 study published in the Mayo Clinic Proceedings 1.
- It's also important to note that bicarbonate therapy should be used with caution in patients with heart failure or fluid overload due to the sodium load, as mentioned in the example answer.
- The 2018 expert consensus document on the management of hyperkalaemia in patients with cardiovascular disease treated with renin angiotensin aldosterone system inhibitors, published in the European Heart Journal, also recommends the use of sodium bicarbonate to promote potassium elimination in patients with metabolic acidosis 1.
From the Research
Purpose of Bicarbonate in Hyperkalemia
The purpose of bicarbonate in hyperkalemia is to help lower plasma potassium levels.
- Bicarbonate can lower plasma potassium independent of its effect on blood pH 2.
- A study found that bicarbonate treatment lowered plasma potassium levels in hyperkalemic patients, even when blood pH remained constant 2.
- However, a more recent systematic review and meta-analysis found that the use of bicarbonate had no effect on potassium levels, with very low certainty of evidence 3.
Mechanism of Action
- Bicarbonate helps shift extracellular potassium into cells, which can help lower plasma potassium levels 2.
- The correlation between changes in plasma potassium and bicarbonate is independent of urinary potassium excretion 2.
Clinical Use
- Bicarbonate should be used to treat hyperkalemia in compensated acid-base disorders, even in the presence of renal failure, provided the plasma bicarbonate concentration is decreased 2.
- However, the most recent evidence suggests that treatment with insulin in combination with glucose, inhaled or intravenous salbutamol, or the combination is supported, while no evidence supports a clinical effect of calcium or bicarbonate for hyperkalemia 3.