Magnesium
Measures magnesium levels in blood to assess electrolyte balance, muscle function, and heart health.
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LevelPanel has no business or affiliate relationship with Quest or LabCorp. These links are provided as a public service.
Lab testing services linked from this site are not available to residents of Alaska, Arizona, or Hawaii, unless otherwise noted on the lab's own website.
This publication is not intended to solicit the purchase of laboratory testing from any individual consumer.
What this test measures
Magnesium is involved in hundreds of enzymatic reactions throughout the body, making it one of the most versatile minerals in human physiology. It is required for normal muscle contraction and relaxation, nerve impulse transmission, bone mineralization, heart rhythm stability, blood pressure regulation, blood sugar management, and immune defense.
Approximately 60% of the body's magnesium resides in bone, with most of the remainder distributed across muscles and soft tissues. Only about 1% circulates in the blood, which is what this test measures. That small circulating fraction is tightly regulated, so serum magnesium can sometimes appear normal even when total body stores are depleted. Despite this limitation, the test remains a practical first-line tool for evaluating magnesium status, particularly when symptoms like muscle cramps, tremors, or irregular heartbeat suggest an electrolyte imbalance.
Who should consider this test
You might consider this test if you are experiencing any of the following:
- Individuals experiencing unexplained muscle cramps, weakness, fatigue, or irregular heartbeat symptoms
- People with kidney disease, diabetes, or digestive disorders that may affect magnesium absorption or excretion
- Those taking medications such as diuretics, proton pump inhibitors, or certain antibiotics that can alter magnesium levels
- Individuals with chronic alcoholism or malnutrition who may have depleted magnesium stores
- People with abnormal levels of other electrolytes like calcium or potassium, as magnesium affects their balance
- Those experiencing symptoms like nausea, confusion, or numbness that could indicate electrolyte imbalances
What to expect
Preparation
There's usually no preparation for a magnesium blood test. If you're having other blood tests at the same time, you may need to fast (not eat or drink) for several hours before your test. It's important to inform the healthcare provider about all medications, supplements, and herbs being taken, as some can affect magnesium levels.
Sample Type
A standard blood sample is collected from a vein in the arm using a small needle.
Collection
A health care professional will take a blood sample from a vein in your arm, using a small needle. After the needle is inserted, a small amount of blood will be collected into a test tube or vial. You may feel a little sting when the needle goes in or out. This usually takes less than five minutes.
Turnaround
Results are typically available within 1-2 business days after the sample reaches the laboratory.
Understanding your results
Serum magnesium results help healthcare providers assess electrolyte balance and investigate symptoms such as persistent muscle cramps, cardiac arrhythmias, or unexplained weakness. One important caveat: because the blood contains only a tiny fraction of the body's total magnesium, a normal serum level does not completely rule out a whole-body deficit. This is why providers weigh results alongside clinical symptoms, dietary history, kidney function, and any medications that may affect magnesium absorption or excretion.
| Population | Reference Range | Notes |
|---|---|---|
| Adults | 1.7 - 2.2 mg/dL (0.70 - 0.91 mmol/L) | The normal range for blood magnesium level is 1.7 to 2.2 mg/dL (0.70 to 0.91 mmol/L). |
Reference ranges shown are general guidelines. Your lab report will include the specific reference range used by the laboratory that processed your sample, which is the authoritative range for interpreting your results.
What does a “Low” result mean?
Loss of appetite, nausea, vomiting, fatigue, and weakness are some of the early signs and symptoms of magnesium deficiency. As the condition progresses, people with magnesium deficiency may experience numbness, muscle contractions and cramps, seizures, abnormal heart rhythms, coronary spasms, and other symptoms. Low magnesium levels may be associated with poor dietary intake, malabsorption disorders, certain medications, chronic alcoholism, or kidney problems that cause excessive magnesium loss.
What does a “High” result mean?
Hypermagnesemia is an electrolyte disorder: a high magnesium level in your blood. Kidney failure is the most common cause. Symptoms include weakness, confusion, decreased breathing rate, and decreased reflexes. Complications may include low blood pressure and cardiac arrest. Other potential causes of elevated magnesium may include excessive intake of magnesium-containing medications such as antacids or laxatives, certain endocrine disorders, or dehydration.
Privacy & confidentiality
All test orders are authorized and results reviewed by an independent, board-certified physician who is not the patient's personal doctor. LevelPanel provides complete confidentiality for all magnesium testing. Results are delivered directly to individuals through a secure online portal and are <u>not reported to your doctor</u> unless you choose to share them. Test results are <u>not part of your medical records</u> and will <u>not appear on insurance statements</u> or explanations of benefits (EOB). This testing is conducted with no doctor visit required, allowing individuals to assess their magnesium status privately. Your employer, insurance company, and healthcare providers will have no knowledge of your testing unless you decide to share the information with them. We understand that some individuals prefer to monitor their health markers discretely, whether for personal wellness tracking or before discussing concerns with their healthcare provider. Our confidential testing process ensures that you maintain complete control over your health information while getting the reliable lab results you need.
Frequently asked questions
Related tests
Comprehensive Metabolic Panel (CMP)
Includes basic electrolytes and can help identify broader metabolic issues that may affect magnesium balance
View TestCalcium Test
Magnesium and calcium levels are closely related, and abnormal magnesium can cause calcium imbalances
View TestPotassium Test
Magnesium deficiency can cause potassium deficiency, and both minerals work together in muscle and heart function
View TestRelated conditions
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Last reviewed: April 2026
CPT Code: 83735
This test may not be available in: NY, NJ, RI
This page is for informational purposes only and does not constitute medical advice. Always consult with a healthcare provider regarding any health concerns. LevelPanel does not diagnose, treat, or prescribe.
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LevelPanel has no business or affiliate relationship with Quest or LabCorp. These links are provided as a public service.
Lab testing services linked from this site are not available to residents of Alaska, Arizona, or Hawaii, unless otherwise noted on the lab's own website.
This publication is not intended to solicit the purchase of laboratory testing from any individual consumer.
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