Potassium (K+)
BMP / ElectrolytesNormal range
3.5–5.0 mEq/L
SI: 3.5–5.0 mmol/L
Critical low: < 2.5 mEq/L · Critical high: > 6.5 mEq/L
☎ When to call
K > 6.0 or < 2.8, any abnormal K with ECG changes, or a hemolysis-implausible jump — call now. Hyperkalemia with ECG changes is a code waiting to happen.
What you do
- Get an ECG / telemetry with any abnormal K — peaked T waves (high), flat T/U waves (low)
- High: hold K-containing meds; anticipate calcium gluconate, insulin+D50, kayexalate/dialysis
- Low: NEVER IV push potassium — infusion max typically 10 mEq/hr on a pump peripherally (verify policy)
- If hemolysis is plausible, redraw before treating a surprise high
Causes of HIGH potassium
Causes of LOW potassium
Source: Pagana, Mosby's Manual of Diagnostic and Laboratory Tests, 7th ed.Reference only — verify against your facility's policy.
