Skip to content

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, blood pressure regulation, and bone health."]

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

Key facts at a glance

LOINC
17234-6
Short code
Magnesium SerPl/RBC Bld-sRto
Synonyms
Magnesium SerPl/RBC Bld-sRto
Category
hematology
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 Is This Test Done?

Your healthcare provider may order this test to check for low or high magnesium levels, which can occur due to conditions like kidney problems, vomiting, diarrhea, or certain medications. It may also be done to monitor magnesium levels during treatment for conditions like heart rhythm issues or seizures.

What to Expect Before the Test

No special preparation is usually needed. You may be asked to fast for 8–12 hours before the test if your provider specifies it, but this is not always required. Bring any medications or supplements you’re taking to your appointment.

What Happens During the Test?

A healthcare professional will draw blood from a vein in your arm. You may feel a slight pinch or discomfort, but it usually lasts only a few seconds. The test itself is quick and painless.

What Do the Results Mean?

Results help determine if your magnesium levels are too low (hypomagnesemia) or too high (hypermagnesiumemia). These imbalances can affect muscle function, heart rhythm, or other health issues. Your provider will interpret results in the context of your overall health.

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

How often do I need this test?
Your provider will decide how often you need this test based on your medical history, symptoms, and treatment plan. Some people may need it only once, while others may need regular monitoring.
What causes magnesium levels to change?
Magnesium levels can be affected by diet (low intake or excessive loss), certain medications, kidney function, vomiting, diarrhea, or medical conditions like diabetes or heart disease. Lifestyle factors, such as alcohol use or stress, may also play a role.
Can I adjust my diet to help balance magnesium levels?
Yes, foods rich in magnesium—like leafy greens, nuts, seeds, whole grains, and legumes—can help maintain healthy levels. However, avoid excessive supplements unless directed by your provider, as too much can be harmful.
  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