Magnesium, Serum or Plasma Concentration
This test measures the amount of magnesium, a mineral essential for many bodily functions, including muscle and nerve function, blood pressure regulation, and energy production.
["Magnesium helps your body stay balanced, but levels can vary based on diet, health conditions, or medications."]
Key facts at a glance
- LOINC
- 26746-8
- Short code
- Magnesium RBC-mCnc
- Synonyms
- Magnesium RBC-mCnc
- Category
- electrolyte
- Sample
- whole-blood
- Container
- Lavender-top (EDTA)
- Units
- N/A
- Ref low
- 1.7
- Ref high
- 2.2
- Critical range
- 1 N/A – 5 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- CPT
- 83735
- SNOMED
- 900000000000003001
- Specimen volume
- 3 mL
- Stability
- Room temperature: 4h, Refrigerated: 24h
- Hemolysis max
- 0
- Lipemia max
- 0
- Icterus max
- 0
- TAT
- 4–24 hours
- Order
- routine
Why Might You Need This Test?
Your healthcare provider may order this test if you have symptoms like muscle cramps, weakness, irregular heartbeat, or conditions such as kidney disease, diabetes, or certain heart or muscle disorders. It may also be checked during pregnancy, if you’re taking certain medications (like antibiotics or diuretics), or if you have unexplained fatigue or bone pain.
What to Expect Before the Test
No special preparation is usually needed, but you may be asked to fast for 8–12 hours before the test if it’s drawn from your blood. If it’s a urine test, you might need to collect a sample over 24 hours. Always follow your provider’s instructions.
What Happens During the Test?
For blood tests, a small needle is used to draw blood from a vein in your arm. For urine tests, you’ll collect a sample in a container. The sample is then sent to a lab for analysis.
What Are Possible Results?
Results are compared to a reference range specific to your lab, which accounts for factors like age, sex, and health status. Low or high levels may signal underlying issues that need further evaluation.
Reference range
Adult: 1.7-2.2 mg/dLN/A
No special preparation required. Stay well hydrated.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Low magnesium levels (hypomagnesemia) can cause muscle spasms, seizures, irregular heartbeat, or weakened bones. High levels (hypermagnesemia) are less common but may lead to nausea, low blood pressure, or slowed breathing. Both extremes can affect other health conditions, so results are reviewed by your provider.
Short name
Magnesium Level
Frequently asked questions
What Causes Low or High Magnesium Levels?
How Does My Doctor Use This Test?
Can I Adjust My Diet Before the Test?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.
This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy