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Serum Magnesium Concentration (Mass Concentration)

Published: August 9, 2026Updated: August 16, 2026

This test measures the amount of magnesium, a mineral essential for many bodily functions, in your blood serum.

Quick summary

["Magnesium helps with muscle and nerve function, blood pressure, and bone health."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
108977-0
Short code
M agalactiae Ab Msmt Ser
Synonyms
M agalactiae Ab Msmt Ser
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
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 Might You Need This Test?

Your doctor may order this test to check for low or high magnesium levels, which can affect heart rhythm, muscle function, or other health conditions like kidney disease or certain medications.

What Does the Test Involve?

You’ll have a small needle inserted into your arm or vein to draw blood. The blood sample is then sent to a lab for analysis.

What Are Common Reasons for Testing?

Common reasons include diagnosing or monitoring conditions like hypomagnesemia (low magnesium), hypermagnesemia (high magnesium), muscle cramps, irregular heartbeat, or evaluating kidney function.

How Is the Test Performed?

The test is typically done by a healthcare professional who collects a blood sample. The blood is processed to separate serum, which is then analyzed for magnesium levels.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Serum Magnesium

Frequently asked questions

Magnesium is crucial for nerve and muscle function, blood pressure regulation, and bone health. Abnormal levels can cause symptoms like muscle spasms, weakness, or heart problems. Low magnesium may also be linked to conditions like diabetes or kidney disease.
How long does it take to get results?
Results are usually available within 1 to 3 business days, depending on your lab’s processing time.
What are typical symptoms of low or high magnesium?
Low magnesium may cause muscle twitches, cramps, or fatigue. High magnesium levels can lead to nausea, irregular heartbeat, or muscle weakness. Symptoms vary and may not appear until levels are significantly out of range.
For most magnesium tests, you can eat and drink normally unless your doctor specifies otherwise. Follow any fasting instructions they provide to avoid unnecessary variations in results.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

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.

Medical Disclaimer

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