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Magnesium, Serum 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.

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
87470-1
Short code
Magnesium Spec-mCnt
Synonyms
Magnesium Spec-mCnt
Category
electrolyte
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
1.7
Ref high
2.2
Critical range
1 N/A – 5 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
83735
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 Might This Test Be Ordered?

Your doctor may order this test to check for low or high magnesium levels, which can occur due to conditions like kidney problems, certain medications, or dietary deficiencies. It may also be done if you have symptoms like muscle weakness, cramps, irregular heartbeat, or numbness.

What to Expect Before the Test

No special preparation is usually needed, but you may be asked to fast for a few hours before the blood draw if your doctor specifies. Bring any medications you’re currently taking to your appointment.

What the Test Results Mean

Results help determine if your magnesium levels are within a healthy range. Abnormal levels can indicate underlying health issues that need medical attention.

Common Conditions Linked to Magnesium Imbalances

Low magnesium (hypomagnesemia) can be linked to conditions like kidney disease, diabetes, or certain medications. High magnesium (hypermagnesemia) is less common but can occur with kidney problems or excessive intake.

Reference range

Adult: 1.7-2.2 mg/dLN/A

Specimen: serum

No special preparation required. Stay well hydrated.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Serum Magnesium Level

Frequently asked questions

What causes low magnesium levels?
Low magnesium levels may result from poor diet (low intake of foods like nuts, leafy greens, or whole grains), kidney problems that don’t properly remove magnesium from the body, or certain medications (e.g., diuretics). Chronic vomiting, diarrhea, or alcohol use can also deplete magnesium stores.
What are the symptoms of low magnesium?
Symptoms of low magnesium may include muscle twitches or cramps, weakness, irregular heartbeat, numbness, or even seizures in severe cases. Some people may not notice symptoms until levels are very low.
How is magnesium usually treated?
Treatment for low magnesium often involves dietary changes (eating magnesium-rich foods) or oral supplements if needed. Severe cases may require intravenous magnesium therapy under medical supervision. High magnesium levels are less common and may require treatment based on the underlying cause.
  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