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Serum Magnesium 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. Low or high levels may indicate underlying health concerns.

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
109984-5
Short code
M-IgG Msmt Ser
Synonyms
M-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 weakness, cramps, or irregular heartbeat. It could also be part of routine check-ups, especially if you have conditions like kidney disease, diabetes, or heart problems. Additionally, it may be used to monitor treatment for conditions affecting electrolyte balance or to check for deficiencies or excesses of magnesium in your body.

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 metabolic panel. On the day of the test, avoid excessive alcohol or caffeine, as they can sometimes affect magnesium levels. Bring any medications you’re currently taking to your appointment.

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 the process is quick and typically painless. 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 levels may raise concerns about muscle or nerve function, while high levels could indicate kidney issues or other health problems. Your provider will discuss the results in the context of your overall health and symptoms.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance of Magnesium Levels

Short name

Magnesium Level

Frequently asked questions

What Are Common Causes of Low Magnesium?
Low magnesium levels can be caused by conditions like diarrhea, vomiting, or kidney problems that don’t properly absorb or retain magnesium. Certain medications, such as diuretics or antacids, may also deplete magnesium. Poor diet (low intake of foods like nuts, leafy greens, or whole grains) can contribute, as well as chronic alcohol use.
What Are Common Causes of High Magnesium?
High magnesium levels are less common but can result from kidney failure, excessive intake of magnesium supplements, or certain medications. Rarely, it may be linked to conditions like Addison’s disease or severe dehydration. Your provider will evaluate your symptoms and medical history to determine the cause.
How Often Should I Get This Test?
This test is typically ordered as needed, depending on your symptoms or medical condition. If you have chronic health issues like kidney disease or diabetes, your provider may recommend regular monitoring. Otherwise, it’s usually not part of routine annual check-ups unless advised otherwise.
  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