What it means
The main positive ion inside the body's cells. Small changes in the blood level change how muscles and the heart's electrical system behave, which is why the serum potassium is one of the most watched lab values. The kidneys control it, so kidney problems, diuretics and vomiting or diarrhea all move it. A low level is hypokalemiahy-poh-kuh-LEE-mee-uhA blood potassium level below normal, under 3.5 mEq/L.hypo- belowkal potassium (from its Latin name, kalium)-emia in the bloodFull entry ; a high level is hyperkalemiahy-per-kuh-LEE-mee-uhA blood potassium level above normal, over 5.0 mEq/L.hyper- abovekal potassium (from its Latin name, kalium)-emia in the bloodFull entry .
For the nurse
Check the level before giving drugs that change it (loop and thiazide diuretics, digoxin, potassium supplements) and report a value outside the normal range. Potassium chloride for injection is never given by IV push: it is always diluted and run on a pump.
Remember it
Potassium keeps the heart's rhythm: too little or too much and the heart stumbles.
At a glance
| Normal range | 3.5–5.0 mEq/L [3.5–5.0 mmol/L] |
|---|---|
| Critical range | Below 2.5 or above 6.5 mEq/L [below 2.5 or above 6.5 mmol/L]; each lab sets its own critical values. |
| Abbreviations | K, K+ (chemical symbol); KCl (potassium chloride) |
| Spanish | potasio |
Related terms
hypokalemia
A blood potassium level below normal, under 3.5 mEq/L.
hyperkalemia
A blood potassium level above normal, over 5.0 mEq/L.
furosemide
A loop diuretic: a drug that makes the kidneys remove more salt and water from the body.
digoxin
A drug that makes the heart beat more strongly and more slowly.