How much insulin should be used to treat hyperkalemia?
I think of insulin like a key that unlocks a door in cell membranes to allow glucose, potassium, and water to walk through. Putting the potassium in the intracellular space hides it from the heart temporarily and is a critical part of the treatment of hyperkalemia.
While the standard dose of insulin to treat hyperkalemia is 10 units, this dose may result in excessive hypoglycemia in patients with renal insufficiency.
The dose of 10 units is also completely arbitrary and has never been subjected to a dose-finding study.
In a retrospective study from Rush University Medical Center that compared 5 vs 10 units of insulin in patients with renal insufficiency and hyperkalemia, hypoglycemia occurred in 19.5% of patients who received 5 units of insulin and 28.6% of patients who received 10 units. This was a statistically significant difference. The change in serum potassium was similar between groups with a decrease of 0.8 mEq/L in the 5 unit group and a decrease of 0.7 mEq/L in the 10 unit group.
Besides decreasing the dose of insulin given, some clinicians choose to increase the amount of dextrose given to avoid hypoglycemia. For example, some give 50 grams of dextrose as opposed to just 25 grams after giving insulin for hyperkalemia.
Either way, be alert to the possibility of hypoglycemia occurring in patients with renal insufficiency treated with insulin for hyperkalemia, even if they received supplemental dextrose.
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