Skip to content

Mass concentration of magnesium in serum/plasma

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
13010-4
Short code
MAK Bld-mCnc
Synonyms
MAK Bld-mCnc
Category
chemistry
Sample
whole-blood
Container
Lavender-top (EDTA)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Specimen volume
3 mL
Stability
Room temperature: 4h, Refrigerated: 24h
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
4–24 hours
Order
routine

Why Is This Test Done?

Your healthcare provider may order this test to check for low or high magnesium levels, which can affect muscle function, nerve signals, heart rhythm, and bone health. It may also be used to monitor conditions like kidney disease, heart problems, or certain medications that affect magnesium levels.

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’s part of a broader blood panel. Bring any medications or supplements you’re taking, as they could influence results.

What Happens During the Test?

A healthcare professional will draw blood from a vein in your arm using a small needle. You may feel a slight pinch, but it usually doesn’t cause discomfort. The blood sample is then sent to a lab for analysis.

What the Results Mean

Results are compared to standard reference ranges, but exact values can vary by lab. Low magnesium (hypomagnesemia) may cause muscle cramps, weakness, or irregular heartbeats, while high levels (hypermagnesium) can lead to fatigue, nausea, or slowed reflexes.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Serum Magnesium Level

Frequently asked questions

How long does it take to get my results?
Results are typically available within 1–3 business days, depending on your lab’s processing time. Your provider will discuss them with you during your follow-up visit.
Can I eat or drink before this test?
If fasting is required (e.g., for a full blood panel), avoid food and liquids—except water—for 8–12 hours before drawing blood. If fasting isn’t needed, you can eat normally, but avoid caffeine or alcohol before testing.
What if my magnesium level is out of range?
If your results are low, your doctor may recommend dietary changes (e.g., foods like spinach, nuts, or fortified cereals), supplements (under medical supervision), or adjustments to medications. High levels may require lifestyle changes or treatment for the underlying cause, such as kidney issues or overuse of magnesium supplements.
  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