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Magnesium, Serum

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
109630-4
Short code
Magnesium Msmt RBC
Synonyms
Magnesium Msmt RBC
Category
electrolyte
Sample
whole-blood
Container
Lavender-top (EDTA)
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
SNOMED
900000000000003001
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 Might You Need This Test?

Your healthcare provider may order this test to check for low or high magnesium levels, which can affect muscle spasms, heart rhythm, or other health issues. It may also be done if you have symptoms like weakness, cramps, or irregular heartbeat, or if you’re taking certain medications that affect magnesium levels.

What to Expect During the Test

A small blood sample is taken from a vein in your arm. You may feel a slight pinch, but it usually doesn’t cause discomfort. The test is quick and done in a clinic or lab.

Common Causes of Abnormal Results

Low magnesium levels (hypomagnesemia) can result from poor diet, certain medications, kidney problems, or excessive sweating. High levels (hypermagnesemia) are less common but may occur with kidney failure, overuse of magnesium supplements, or certain medical conditions.

How Results Are Used in Care

Your results help doctors diagnose conditions like muscle disorders, heart problems, or electrolyte imbalances. They also guide treatment plans, such as dietary changes or medication adjustments.

Reference range

Adult: 1.7-2.2 mg/dLN/A

Specimen: whole-blood

No special preparation required. Stay well hydrated.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Magnesium Level

Frequently asked questions

What does a low magnesium level mean?
A low magnesium level may indicate an underlying health issue, such as poor nutrient absorption, kidney problems, or certain medications affecting your body’s magnesium balance. It could also be due to excessive sweating or a diet lacking magnesium-rich foods.
How can I naturally increase my magnesium levels?
Eating foods like leafy greens, nuts, seeds, whole grains, and legumes can help boost magnesium. Staying hydrated and avoiding excessive alcohol or caffeine may also support better magnesium balance.
Can magnesium supplements be dangerous if taken too much?
While magnesium supplements can help, taking too much can cause nausea, diarrhea, or irregular heartbeat. Always follow your doctor’s advice on dosage and consult them before starting new 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