Magnesium
Everything you need to know about Magnesium levels, including what normal ranges look like and what abnormal results might indicate.
Standard Reference Range
Unit: mg/dLReference ranges may vary slightly between laboratories. Always consult your doctor for interpretation.
What is Magnesium?
Magnesium is the fourth most abundant mineral in the body, crucial for over 300 enzymatic reactions, muscle and nerve function, blood pressure regulation, and bone health.
Key Takeaway
Magnesium deficiency is common but often overlooked. It can cause resistant hypokalemia and hypocalcemia that won't resolve without magnesium replacement.
Why is this test performed?
Magnesium testing helps:
- Investigate resistant low potassium or calcium
- Evaluate muscle weakness or cramps
- Assess cardiac arrhythmias
- Monitor malabsorption disorders
- Check chronic diarrhea effects
Interpreting Your Results
Low Magnesium (Hypomagnesemia)
＜1.7 mg/dL indicates low magnesium:
Symptoms:
- Muscle cramps, tremors
- Weakness, fatigue
- Irregular heartbeat
- Seizures (severe)
- Personality changes
- Nausea, loss of appetite
Common Causes:
-
GI losses:
- Chronic diarrhea
- Malabsorption (Crohn's, celiac)
- Chronic alcoholism
-
Renal losses:
- Diuretics (loop, thiazide)
- Diabetes (glycosuria)
- Medications (PPI, aminoglycosides)
-
Other:
- Poor dietary intake
- Chronic stress
- Elderly populations
High Magnesium (Hypermagnesemia)
＞2.2 mg/dL indicates high magnesium:
Symptoms (usually ＞4 mg/dL):
- Nausea, vomiting
- Weakness
- Low blood pressure
- Slow reflexes
- Respiratory depression (severe)
- Cardiac arrest (＞12 mg/dL)
Common Causes:
- Kidney failure (most common)
- Excessive supplementation
- Magnesium-containing antacids/laxatives
- Rare: tumor lysis syndrome
Clinical Significance
Relationship with Other Electrolytes:
- Low magnesium → resistant hypokalemia
- Low magnesium → resistant hypocalcemia
- Must correct magnesium first before K/Ca normalize
Cardiac Effects:
- Hypomagnesemia: Arrhythmias, digitalis toxicity
- Hypermagnesemia: Heart block, cardiac arrest
Treatment
For Hypomagnesemia:
- Mild: Oral magnesium supplements
- Magnesium oxide (poorly absorbed)
- Magnesium glycinate/citrate (better absorbed)
- Severe: IV magnesium sulfate
- Increase dietary magnesium
Magnesium-Rich Foods:
- Dark leafy greens
- Nuts and seeds
- Whole grains
- Legumes
- Dark chocolate
- Avocados
For Hypermagnesemia:
- Stop magnesium sources
- IV fluids and diuretics
- Dialysis (if kidney failure)
- Calcium gluconate (cardiac protection)
Important Notes
- Serum magnesium doesn't reflect total body stores well
- Intracellular magnesium can be low with normal serum levels
- Consider supplementation even with borderline levels if symptomatic
Related Tests
- Potassium: Often low together
- Calcium: Affected by magnesium
- Creatinine: Check kidney function
- Vitamin D: Works with magnesium
Decode your Serum Magnesium Results
Upload your PDF report to WellAlly. AI will visualize your trends and provide personalized health insights instantly.