What It Measures
This test measures the concentration of magnesium in the blood serum. Since only about 1% of the body's magnesium circulates in the blood (with ~60% stored in bones and ~39% in soft tissues and muscles), serum levels can appear normal even when total body magnesium is depleted. It reflects recent dietary intake and renal handling of magnesium.
Magnesium is an essential mineral involved in over 300 enzymatic reactions in the body, including energy production, muscle and nerve function, blood sugar control, and blood pressure regulation. It is the fourth most abundant mineral in the body and is critical for cardiovascular health, bone integrity, and metabolic function. Serum magnesium testing measures only ~1% of total body magnesium, making it an imperfect but clinically useful marker.
Current Value
What High Means
Elevated serum magnesium (hypermagnesemia) is relatively rare and usually occurs in the context of kidney failure (impaired renal excretion), excessive supplementation or IV magnesium administration, or use of magnesium-containing antacids/laxatives. It can also be seen with adrenal insufficiency, hypothyroidism, and lithium therapy. Severe hypermagnesemia can depress the neuromuscular and cardiovascular systems, potentially causing cardiac arrest.
Possible Symptoms
Nausea, vomiting, facial flushing, hypotension (low blood pressure), bradycardia (slow heart rate), muscle weakness, lethargy, diminished deep tendon reflexes, respiratory depression, cardiac arrhythmias, cardiac arrest in severe cases
What Low Means
Low serum magnesium (hypomagnesemia) is common, affecting an estimated 10-30% of the general population. Causes include inadequate dietary intake, GI losses (diarrhea, malabsorption, celiac disease), renal wasting (diuretics, alcohol use, diabetes), and medications like proton pump inhibitors. Chronic low magnesium is associated with increased risk of type 2 diabetes, cardiovascular disease, osteoporosis, migraines, anxiety, depression, and metabolic syndrome. It also impairs calcium and potassium homeostasis.
Possible Symptoms
Muscle cramps, twitching, and spasms; fatigue and weakness; numbness and tingling; heart palpitations and arrhythmias; anxiety, irritability, and mood changes; insomnia and poor sleep quality; headaches and migraines; constipation; poor appetite; brain fog and difficulty concentrating
Risk Factors
Type 2 diabetes and insulin resistance, cardiovascular disease (arrhythmias, hypertension, coronary artery disease), osteoporosis, chronic kidney disease, migraines, depression and anxiety, metabolic syndrome, muscle cramps and spasms, preeclampsia, asthma, ADHD, Alzheimer's disease risk
Actionable Advice
Supplements
- •Magnesium Glycinate
- •Magnesium L-Threonate
- •Magnesium Taurate
- •Magnesium Malate
- •Magnesium Citrate
- •Magnesium Chloride (topical)
Diet & Lifestyle
- •Eat magnesium-rich foods: dark leafy greens (spinach, Swiss chard), pumpkin seeds, almonds, dark chocolate (70%+), avocado, black beans
- •Limit alcohol consumption, which increases renal magnesium excretion
- •Reduce processed food intake — food processing removes up to 80% of magnesium
- •Consider splitting magnesium supplements into 2-3 doses throughout the day for better absorption
- •Take magnesium glycinate or threonate before bed to support sleep quality
- •Ensure adequate vitamin D and B6 intake, which support magnesium absorption and utilization
- •Minimize chronic stress, which depletes magnesium stores
- •If taking PPIs or diuretics long-term, monitor magnesium levels regularly
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Historical Trend
Related Biomarkers
Resources & Studies
All Readings
| Date | Value | Change |
|---|---|---|
| 2026-01-28 | 6.1 mg/dL | 0.0 |
| 2025-08-25 | 6.1 mg/dL | — |