Normal potassium is 3.5 to 5.0 mEq/L. Too much or too little can stop the heart, so potassium questions are everywhere on nursing exams.
Side by side
| High (over 5.0) | Low (under 3.5) | |
|---|---|---|
| Common causes | Kidney failure, ACE inhibitors, potassium-sparing diuretics, tissue injury, acidosis | Loop and thiazide diuretics, vomiting, diarrhea, NG suction |
| Symptoms | Muscle weakness, tingling, slow heart rate | Muscle weakness and cramps, constipation, fatigue |
| EKG | Tall, peaked T waves, then a wide QRS | Flat T waves, U waves, ST depression |
| Danger | Ventricular fibrillation, cardiac arrest | Dangerous rhythms, and digoxin toxicity |
Treating high potassium
- Put the patient on a cardiac monitor.
- Calcium gluconate IV protects the heart first. It does not lower the potassium.
- Regular insulin IV with dextrose moves potassium into the cells. Albuterol can help too.
- Remove it from the body: potassium binders, loop diuretics, or dialysis.
- Stop potassium sources, such as supplements and salt substitutes.
Treating low potassium
- Oral potassium chloride when possible.
- IV potassium is never given as an IV push. Always dilute it and run it on a pump. A common maximum through a peripheral IV is 10 mEq per hour. Follow your facility's policy.
- Make sure the patient is urinating before giving IV potassium.
- Check magnesium. Low magnesium makes low potassium hard to correct.
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Quick answers
What EKG change happens with hyperkalemia?
Tall, peaked T waves are the classic sign. As potassium rises further, the QRS widens.
Can you give potassium IV push?
No. IV potassium is never given as a push. It must be diluted and given on an infusion pump.
Evidence & Clinical Sources
- MedlinePlus lab tests
- Vallerand & Sanoski, Davis's Drug Guide for Nurses, F.A. Davis
- Hinkle & Cheever, Brunner & Suddarth's Textbook of Medical-Surgical Nursing, Wolters Kluwer
Reviewed against current guidelines and drug labels. Always follow your program, a current drug reference, and facility policy. Our sources policy
For learning only. Lab ranges and policies vary. Always follow your nursing program, a current drug reference, and your facility's policies.