What is Magnesium?
Magnesium is an essential mineral and a cofactor in over 300 enzymatic reactions, including energy production, muscle and nerve function, blood glucose control, and blood pressure regulation. Because most magnesium is inside cells and bone, serum levels can appear normal even when body stores are low.
Why it matters
Magnesium supports heart rhythm, muscle relaxation, and insulin sensitivity. Deficiency is common with poor diet, certain medications, and GI or kidney conditions, and is associated with muscle cramps, arrhythmias, and worse metabolic health.
What it measures
Serum magnesium (most common). RBC magnesium may better reflect cellular stores, since serum is tightly regulated.
Reference & optimal ranges
Reference ranges vary by lab, assay, age, and sex. The ranges below reflect commonly published adult intervals and are for education only always interpret results with the range printed on your own lab report and a clinician.
High magnesium is uncommon and usually seen with kidney impairment or excessive supplement/antacid use.
Common symptoms
- Nausea
- Low blood pressure
- Muscle weakness
- Slow heart rate (severe)
Potential causes
- Kidney failure
- Excess magnesium-containing antacids or laxatives
- Excessive supplementation
Low magnesium can cause muscle and nerve symptoms and arrhythmias, and often coexists with low potassium and calcium.
Common symptoms
- Muscle cramps and twitching
- Fatigue
- Palpitations / arrhythmia
- Numbness or tingling
- Poor sleep, anxiety
Potential causes
- Poor dietary intake
- Alcohol use
- GI losses (diarrhea, malabsorption)
- Diuretics or proton-pump inhibitors
- Uncontrolled diabetes
How to improve your Magnesium
Lifestyle
Limit heavy alcohol
Alcohol increases magnesium loss through the kidneys.
Nutrition
Magnesium-rich foods
Nuts, seeds, legumes, whole grains, and leafy greens are excellent sources; supplement if intake is low.
Exercise
Replace losses
Heavy sweating increases magnesium needs in athletes.
Sleep
May support sleep
Correcting deficiency may ease cramps and improve sleep quality.
Frequently asked questions
Scientific references
- Magnesium Fact Sheet for Health Professionals NIH Office of Dietary Supplements (2022)
- Magnesium Blood Test MedlinePlus, U.S. National Library of Medicine
Educational information, not medical advice. This page is for general education and does not replace diagnosis or treatment by a licensed clinician. Do not start, stop, or change any medication, supplement, or treatment based on this content. Reference and optimal ranges vary between laboratories interpret your results with the range on your own report and a qualified professional.