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Serum or plasma concentration of magnesium (mass 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.

Quick summary

["Magnesium helps with muscle and nerve function, bone health, and energy production."]

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

Key facts at a glance

LOINC
90248-6
Short code
MOG IgG1 SerPl Ql FC
Synonyms
MOG IgG1 SerPl Ql FC
Category
glucose
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
flow-cytometry
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

What Is Magnesium Used For?

Magnesium plays a key role in over 300 enzymatic reactions in your body, including muscle contraction, nerve signaling, and energy metabolism. Low levels can affect how your body uses calcium and potassium, potentially leading to muscle cramps, weakness, or irregular heartbeat. High levels may cause nausea, vomiting, or muscle weakness.

Why Might You Need This Test?

Your doctor may order a magnesium test if you have symptoms like muscle spasms, tremors, weakness, or irregular heartbeat. It may also be checked during pregnancy, if you have kidney disease, or if you’re taking 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 you’re taking to your appointment.

What Happens During the Test?

A healthcare provider will draw blood from a vein in your arm. You may feel a slight pinch, but the procedure is quick. The blood sample is sent to a lab for analysis.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Abnormal magnesium levels can indicate underlying health issues, such as kidney problems, diabetes, or certain heart conditions. Low magnesium may also be linked to conditions like hypoparathyroidism or malabsorption disorders. High levels could suggest overuse of supplements or certain medications.

Short name

Magnesium Level

Frequently asked questions

What Are Common Causes of Low Magnesium?
Low magnesium (hypomagnesemia) can result from poor diet (low intake of foods like nuts, leafy greens, or whole grains), kidney disease, vomiting/diarrhea, or certain medications (e.g., diuretics, antibiotics). Chronic alcohol use can also deplete magnesium levels.
What Are Common Causes of High Magnesium?
High magnesium (hypermagnesium) is less common but may occur with kidney failure (where the body can’t excrete excess magnesium), overuse of magnesium supplements, or certain medications (e.g., some antibiotics or laxatives). Rarely, it can be genetic.
How Long Does It Take to Get Results?
Results are typically available within 1–3 business days, depending on your lab. Your doctor will discuss the findings with you during your follow-up visit.
  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