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Serum Magnesium Concentration

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

This test measures the amount of magnesium in your blood serum, an important mineral for muscle and nerve function, bone health, and maintaining normal heart rhythms.

Quick summary

["Magnesium helps with many body functions, and low or high levels may signal health concerns."]

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

Key facts at a glance

LOINC
13664-8
Short code
MAG/SGPG IgM Titr Ser
Synonyms
MAG/SGPG IgM Titr Ser
Category
glucose
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 doctor may recommend this test if you have symptoms like muscle weakness, cramps, or irregular heartbeat, or if you have conditions like kidney disease, diabetes, or certain medications that affect magnesium levels. It may also be part of routine check-ups for people at higher risk of magnesium deficiencies or imbalances.

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 metabolic panel. Bring any medications you’re taking to your appointment.

What the Results Mean

Results are compared to standard reference ranges for healthy adults. Low magnesium levels may indicate dehydration, poor diet, or certain medical conditions, while very high levels could be linked to kidney problems or overuse of supplements.

Common Causes of Abnormal Results

Magnesium levels can drop due to vomiting, diarrhea, excessive sweating, or certain medications (like diuretics). They may rise from kidney disease, overhydration, or conditions like Addison’s disease.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Magnesium is vital for nerve and muscle function, blood pressure regulation, and preventing heart arrhythmias. Low levels can cause weakness, seizures, or irregular heartbeat, while high levels may lead to nausea, confusion, or muscle spasms. Your doctor will interpret results in the context of your overall health and symptoms.

Short name

Magnesium Level

Frequently asked questions

What triggers a magnesium test?
Symptoms like muscle spasms, tingling, or fatigue, or if you have conditions like kidney disease, diabetes, or are taking medications that affect magnesium levels (e.g., antibiotics like gentamicin).
How long does it take to get results?
Results are typically available within 1–3 business days, depending on your lab’s processing time.
Can I eat or drink before this test?
Most often, you’ll need to fast for 8–12 hours before the test, but your doctor or lab will specify if it’s part of a metabolic panel.
  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