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Magnesium, Serum Concentration

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

This test measures the amount of magnesium in your blood serum, a mineral essential for muscle and nerve function, blood pressure regulation, and bone health.

Quick summary

["Magnesium levels help assess potential deficiencies or excesses that could affect your health."]

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

Key facts at a glance

LOINC
87469-3
Short code
Magnesium Spec-mCnc
Synonyms
Magnesium Spec-mCnc
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 Is This Test Done?

Your healthcare provider may order this test if you have symptoms like muscle weakness, cramps, irregular heartbeat, or signs of electrolyte imbalances. It may also be checked during pregnancy, with kidney disease, or if you’re taking certain medications that affect magnesium levels.

What to Expect Before the Test

No special preparation is needed, but you may be asked to fast for 8–12 hours before the test if it’s part of a broader metabolic panel. Bring any medications you’re currently taking to your appointment.

How the Test Is Performed

A blood sample is drawn from a vein, usually in your arm, by a healthcare professional. The serum portion of the blood is then analyzed in a lab to measure magnesium concentration.

Possible Results and Interpretation

Results are compared to standard reference ranges, but individual ranges can vary by lab. Low magnesium (hypomagnesemia) may cause muscle spasms or heart rhythm issues, while very high levels (hypermagnesemia) can lead to weakness or slowed reflexes.

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.

Abnormal magnesium levels can indicate underlying conditions like kidney disease, malnutrition, or certain medications (e.g., diuretics, antacids). Chronic deficiencies may contribute to long-term health risks like heart disease or osteoporosis, while excesses can interfere with other electrolytes.

Short name

Magnesium Level

Frequently asked questions

When might I need this test?
If you experience unexplained muscle twitching, fatigue, or irregular heartbeat, or if your doctor suspects an electrolyte imbalance during a routine checkup.
How long will 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?
Standard fasting guidelines apply (usually 8–12 hours before testing), but always confirm with your provider, as some tests may have exceptions.
  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