Compare conditions

Put any two — or three — conditions side by side, adult or pediatric, to spot the look-alike differences fast, row by row.

Mg (magnesium) disorders

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In one line

·Low magnesium (Mg) from diuretics, alcohol, PPIs, or diarrhea causes stubborn low potassium (K) that won't fix and low calcium (Ca), and can trigger torsades de pointes (a deadly spinning heart rhythm).

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Normal physiology

·Magnesium sits inside every cell and steadies the electrical gates on cell walls, helps hundreds of enzyme workers run the body's chemistry, and keeps potassium and calcium in balance. Picture it as the quiet foreman making sure nerves fire cleanly, muscles contract smoothly, and the heart beats steadily.

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What goes wrong

·Magnesium runs low when the gut can't absorb it (long diarrhea, inflammatory bowel disease, stomach surgery) or the kidney wastes it (diuretics like furosemide, alcohol, proton-pump inhibitors like omeprazole, cisplatin chemo, or a rare genetic tubule defect called Gitelman syndrome). Magnesium climbs too high when someone gets large IV or enema doses (usually magnesium sulfate for eclampsia) and the kidneys can't clear it because of kidney failure.

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Hallmark signs

·Muscle twitches or cramps that won't let up
·Numbness or tingling around the mouth or in the hands and feet
·Heart racing or skipping beats (palpitations)
·Seizure or whole-body shaking you can't control
·Feeling weak all over or trouble moving
·Nausea, throwing up, or losing your appetite
·Confusion or trouble thinking clearly
·Taking medicines like proton-pump inhibitors (PPIs for heartburn), diuretics (water pills), or drinking a lot of alcohol

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Red flags · escalate now

·Heart rhythm suddenly turns very slow, very fast, or chaotic (arrhythmia) on the monitor
·Seizure or uncontrollable shaking
·Muscles so weak the person can't breathe deeply or move at all
·Confusion that gets worse quickly or the person becomes hard to wake up

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Workup

·Serum magnesium (blood test)
·Serum potassium (blood test)
·Serum calcium (blood test)
·12-lead electrocardiogram (EKG)
·24-hour urine magnesium (urine collection test)
·Serum creatinine and estimated glomerular filtration rate (eGFR, kidney function tests)
·Arterial blood gas (ABG)

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Treatment

·IV magnesium sulfate 1 to 2 grams over 1 hour for severe or symptomatic low magnesium; oral magnesium oxide 400 mg once or twice daily for mild, asymptomatic low magnesium
·Find and stop the cause: review and adjust diuretics, stop or reduce PPIs, treat diarrhea, support alcohol cessation
·Replicate potassium (usually 20 to 40 mEq oral or IV) and calcium (1 to 2 grams calcium gluconate IV or oral) after magnesium is corrected
·Continuous cardiac monitor and 12-lead EKG to watch for torsades de pointes or prolonged QT interval
·For high magnesium with symptoms (muscle weakness, lost reflexes, slow heartbeat, trouble breathing): give IV calcium gluconate 1 to 2 grams over 5 minutes, IV loop diuretic (furosemide 20 to 40 mg), and arrange urgent hemodialysis if kidney failure is present or magnesium is very high (above 4 mg/dL)
·Stop magnesium-containing laxatives (like milk of magnesia), antacids (like Maalox), and IV magnesium infusions

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NCLEX trap

·Stop and ask: Why won't the potassium stay up? The answer is almost always low magnesium blocking the potassium gates in the cell wall. Fix magnesium first—potassium will follow. This is the trap that catches nurses who chase the lab number instead of fixing the upstream problem.
·The tremor is a sign of low magnesium—not a seizure disorder. Give magnesium, not sedatives. The twitching will stop when the magnesium is replaced. Sedatives silence the alarm without fixing the problem.
·When potassium and magnesium are low, torsades is a magnesium emergency. Check the magnesium level and give IV magnesium sulfate (MgSO₄). The rhythm will often fix itself once magnesium is replaced. Don't chase the rhythm—fix the electrolyte.
·Diuretics (especially loop and thiazide types), proton-pump inhibitors (PPIs like omeprazole), and alcohol are the big three causes of magnesium loss. If you don't stop the leak, replacing magnesium is like filling a bucket with a hole in the bottom. Find the cause and fix it.
·When magnesium is low, the parathyroid gland (the small glands in the neck that control calcium) can't release parathyroid hormone (PTH) properly, and calcium can't move into cells. Replace magnesium first—calcium will rise on its own as magnesium comes up. Giving calcium alone wastes medicine and misses the real problem.
·Low magnesium makes nerves and muscles fire too easily—everything is jumpy and overexcited. High magnesium does the opposite: it paralyzes nerves and muscles, making everything slow and weak. Read the clinical picture. Shaking, twitching, tight muscles = low (hypomagnesemia). Weak, floppy, no reflexes = high (hypermagnesemia). They are complete opposites.

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