02/17/2026
Potassium is not “just an electrolyte.” It directly affects heart rhythm, muscle function, and patient stability. If you understand potassium, you will catch problems early.
LOW POTASSIUM
Common causes include diuretics, vomiting or diarrhea, poor intake, insulin therapy during DKA, and low magnesium.
Low potassium can cause weakness, cramping, palpitations, ectopy, and worsening arrhythmias.
Do not IV push potassium. Ever.
Why? Potassium affects cardiac conduction. IV push can cause a rapid spike before it circulates and dilutes, which can trigger bradycardia, lethal arrhythmias, asystole, and cardiac arrest.
Replacement is typically PO if tolerated, or IV diluted and run on a pump per facility policy.
A common teaching is 10 mEq may raise potassium about 0.1, but it depends on kidneys, ongoing losses, and acid base status.
If potassium will not improve, check magnesium. Low magnesium makes potassium hard to correct.
HIGH POTASSIUM
Hyperkalemia can look fine until it is not.
Common causes include kidney failure or AKI, missed dialysis, ACE inhibitors, ARBs, spironolactone, acidosis, and tissue breakdown.
First, make sure it is real. Hemolyzed labs can falsely elevate potassium.
If it is real, hyperkalemia can cause peaked T waves, widening QRS, bradycardia, ventricular arrhythmias, and cardiac arrest. Telemetry and an EKG matter.
Treatment goals are protect the heart, shift potassium, then remove potassium.
If indicated, calcium gluconate is given first. It does not lower potassium. It stabilizes the cardiac membrane and buys time.
Then insulin with dextrose shifts potassium into the cells. Monitor glucose closely because hypoglycemia can happen later.
Then remove potassium with diuresis if they can p*e, dialysis if they cannot, and binders as ordered.
Facilities differ, but potassium is commonly treated as a watch closely electrolyte when it is less than 3.0 or greater than 5.5. Meaning they need telemetry!
What is a potassium situation you have seen that made you sweat?
