Magnesium (Mg²⁺)
Normal 1.3–2.1 mEq/LWhy it matters
The gatekeeper — stabilizes K and Ca. Low Mg makes low K and low Ca untreatable until it's fixed.
LOW — Hypomagnesemia (< 1.3)
Causes
Signs
Nursing actions
- Telemetry — torsades is the fear
- Replace per orders (IV mag on a pump)
- Check and fix K and Ca alongside
- Think of it FIRST in withdrawal patients
HIGH — Hypermagnesemia (> 2.1)
Causes
Signs
Nursing actions
- On OB mag drips: reflexes, RR ≥ 12, urine output every check
- Absent patellar reflex or RR < 12 = STOP infusion, call
- Antidote at the bedside: calcium gluconate
Source: Ignatavicius, Medical-Surgical Nursing, 10th ed.Reference only — verify against your facility's policy.
