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Magnesium, Serum 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 levels help assess your body’s mineral balance and overall health."]

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

Key facts at a glance

LOINC
23275-1
Short code
M gallisep Ab Titr Ser
Synonyms
M gallisep Ab Titr Ser
Category
coagulation
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 Is This Test Done?

Your doctor may order this test to check for magnesium deficiency or excess, which can affect muscle function, nerve signals, and heart health. It might also be used to monitor conditions like hypomagnesemia (low magnesium), hypermagnesiumemia (high magnesium), or certain metabolic disorders.

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 involves drawing blood. Avoid consuming magnesium-rich foods or supplements for 24 hours beforehand if instructed by your provider.

What Happens During the Test?

A healthcare professional will draw blood from a vein in your arm. The blood sample is then sent to a lab for analysis using an immunoassay or similar method to measure magnesium levels.

What Do Results Mean?

Results are compared to standard reference ranges for your age, sex, and overall health. Low magnesium levels may cause symptoms like muscle cramps, weakness, or irregular heartbeat, while very high levels can lead to nausea, confusion, or slowed heart rate.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

Serum Magnesium

Frequently asked questions

What Are Common Causes of Abnormal Results?
Low magnesium levels can result from poor diet, kidney disease, vomiting, diarrhea, or certain medications. High levels may occur due to overuse of magnesium supplements, kidney failure, or certain medical conditions like Addison’s disease.
How Often Should This Test Be Done?
The frequency depends on your health status. Your doctor may recommend periodic testing if you have chronic conditions like kidney disease, heart problems, or digestive disorders that affect magnesium absorption.
Can I Avoid This Test?
Not typically—your doctor may order it to monitor your health or diagnose specific issues. If you have concerns, discuss alternatives with your provider.
  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