Magnesium, Serum (Mass Concentration)
This test measures the amount of magnesium, a mineral essential for many bodily functions, in your blood serum. Low or high levels may signal underlying health concerns.
["Magnesium levels help assess kidney function and potential deficiencies or toxicity."]
Key facts at a glance
- LOINC
- 39746-3
- Short code
- NM Kidney Views W Tc99mMAG3 IV
- Synonyms
- NM Kidney Views W Tc99mMAG3 IV
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- nm
- Specimen volume
- 5 mL
- Stability
- Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 4–24 hours
- Order
- routine
Why Is This Test Done?
Your healthcare provider may order this test to check for magnesium imbalances, evaluate kidney function, diagnose conditions like hypomagnesemia (low magnesium) or hypermagnesemia (high magnesium), or monitor treatment responses for conditions like kidney disease, heart rhythm disorders, or certain medications.
What to Expect Before the Test
No special preparation is typically needed. You may be asked to fast for 8–12 hours before the test if instructed by your provider, but this is not always required for magnesium testing. Bring any medications or supplements you take to your appointment.
What Happens During the Test?
A healthcare professional will draw blood from a vein in your arm. The process is quick and usually causes only a minor pinch. The blood sample is sent to a lab for analysis.
What Are Possible Results?
Results are expressed in milligrams per deciliter (mg/dL) or millimoles per liter (mmol/L). While reference ranges vary by lab, low levels may indicate dehydration, kidney disease, or certain digestive disorders, while high levels could suggest kidney problems, overuse of magnesium supplements, or other medical conditions.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Magnesium is critical for nerve and muscle function, blood pressure regulation, and bone health. Low magnesium levels can contribute to muscle cramps, fatigue, irregular heart rhythms, or seizures. High levels may cause nausea, weakness, or abnormal heart rhythms. Chronic imbalances can affect multiple organ systems, including the heart, kidneys, and bones.
Short name
Serum Magnesium
Frequently asked questions
What causes low magnesium levels?
What causes high magnesium levels?
Can I adjust my diet to manage magnesium levels?
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