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

["Your blood magnesium levels help ensure proper nerve and muscle function and support heart health."]

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

Key facts at a glance

LOINC: 23276-9
Short code: M gallisep Ag Spec Ql IF
Synonyms: M gallisep Ag Spec Ql IF
Category: coagulation
Sample: serum
Container: Red-top tube (SST)
Units: N/A
Fasting: false
Population: adult
Sex: all
Age range: 18–65 years
Method: if
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 healthcare provider may order this test if you have symptoms like muscle weakness, cramps, or irregular heartbeat, or if you have conditions like kidney disease, diabetes, or certain heart problems. It may also be part of routine checks for people with chronic illnesses or those taking medications that affect magnesium levels.

What to Expect During the Test

A blood sample is taken from a vein, usually in your arm. You may feel a small pinch, but it’s quick. No special preparation is needed unless instructed otherwise.

Low magnesium (hypomagnesemia) can cause muscle spasms, seizures, or abnormal heart rhythms. High magnesium (hypermagnesium) is less common but may affect heart function or cause nausea. Your levels help diagnose or monitor these conditions.

How Results Are Interpreted

Results are compared to a reference range specific to your lab. While exact values vary, abnormal results may prompt further testing or adjustments to your treatment plan.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Serum Magnesium

Frequently asked questions

What causes my magnesium levels to be checked?

Magnesium levels may be checked if you have symptoms like muscle twitching, fatigue, or irregular heartbeat. It’s also part of evaluations for kidney disease, heart conditions, or if you’re taking certain medications that affect magnesium absorption.

How do magnesium levels affect my health?

Magnesium is vital for nerve and muscle function, blood pressure regulation, and bone health. Low levels can lead to weakness, heart issues, or seizures, while very high levels may cause nausea or heart problems. Your provider will discuss how your results relate to your health.

Can diet or supplements affect my magnesium test results?

Yes, diet (e.g., nuts, leafy greens) and supplements can influence magnesium levels. Avoid taking magnesium-rich supplements 24–48 hours before your test unless instructed by your provider to prevent interference.

Sources

1
MedlinePlus — Laboratory TestsSource
2
Lab Tests OnlineSource
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