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Serum or plasma mass concentration of magnesium

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

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

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
44587-4
Short code
M-IgA Ser Ql IFE
Synonyms
M-IgA Ser Ql IFE
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
immunofixation
CPT
82784
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 a magnesium test to check for low or high levels, which can affect muscle function, nerve signals, and heart health. It’s often done if you have symptoms like muscle cramps, weakness, irregular heartbeat, or conditions like kidney disease, diabetes, or heart problems.

What to Expect Before the Test

No special preparation is usually needed, but you may be asked to fast for a few hours before the blood draw. If you’re on certain medications (like some antibiotics or diuretics), let your doctor know beforehand.

What Happens During the Test?

A healthcare provider will draw blood from a vein in your arm. The sample is sent to a lab for analysis using a method that detects magnesium levels in your serum or plasma.

What Are the Possible Results?

Results are compared to a standard range, but exact values can vary by lab. Low magnesium may cause muscle spasms or heart issues, while very high levels can lead to nausea or irregular heartbeat. Your doctor will interpret results in the context of your health.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Serum Magnesium

Frequently asked questions

What Does a Low Magnesium Level Mean?
Low magnesium (hypomagnesemia) can affect muscle function, cause nerve problems, or worsen conditions like high blood pressure or seizures. It may also indicate kidney problems or poor absorption of nutrients.
What Does a High Magnesium Level Mean?
High magnesium (hypermagnesemia) is less common but can cause nausea, weakness, or slow heart rhythms. It may occur with kidney failure or overuse of magnesium supplements.
How Often Should I Get This Test?
Your doctor will decide based on your symptoms, medical history, or treatment plan. Routine checks aren’t standard unless you have a known risk for magnesium imbalances.
  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