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Serum Magnesium Concentration (Mass Concentration)

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

This test measures the amount of magnesium in your blood serum, an important mineral that helps with muscle and nerve function, blood clotting, and bone health.

Quick summary

["Your doctor may check magnesium levels to monitor health or diagnose conditions like low or high magnesium."]

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

Key facts at a glance

LOINC
108935-8
Short code
LKM IgG Msmt Ser
Synonyms
LKM IgG 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
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 This Test Might Be Ordered

Your healthcare provider may recommend this test if you have symptoms like muscle cramps, weakness, irregular heartbeat, or signs of electrolyte imbalances. It could also be part of routine monitoring for certain medical conditions or treatments.

What to Expect Before the Test

No special preparation is usually needed, but you might be asked to fast for 8–12 hours before the test if it’s part of a metabolic panel. Avoid drinking water right before drawing blood to ensure accurate results.

What Happens During the Test

A healthcare professional will insert a needle into a vein in your arm to draw a small amount of blood. The process is quick and typically painless, though you may feel a brief pinch. The blood sample is then sent to a lab for analysis.

What the Results Mean

Results help determine if your magnesium levels are within the normal range or if they are too high or too low. Abnormal levels can affect how your body uses other minerals and may indicate underlying health issues.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Serum Magnesium

Frequently asked questions

How long does it take to get my test results?
Results are usually available within 1–3 business days, depending on your lab’s processing time. Your doctor will contact you once they’re ready, or you may receive them through your lab’s secure portal.
Can I eat or drink anything before this test?
Most tests don’t require fasting, but if your doctor specified fasting for this test, follow their instructions carefully. If unsure, ask your provider before the appointment.
What are the most common causes of abnormal magnesium levels?
Abnormal magnesium levels can result from poor diet (low intake of foods like nuts, leafy greens, or dairy), kidney problems (which may not remove magnesium properly), certain medications, or conditions like diabetes or alcoholism. Your doctor will discuss potential causes with you based on your medical history.
  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