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Magnesium, Serum or Plasma Mass Concentration

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

This test measures the amount of magnesium in your blood, which helps maintain muscle and nerve function, supports bone health, and plays a role in energy production.

Quick summary

["Magnesium levels can affect muscle cramps, nerve function, and overall health."]

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

Key facts at a glance

LOINC
10880-3
Short code
Magnesium Stl-mCnt
Synonyms
Magnesium Stl-mCnt
Category
electrolyte
Sample
stool
Container
Clean container
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 g
Stability
Refrigerated: 24h, Frozen: 7d
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 cause symptoms like muscle spasms, weakness, irregular heartbeat, or confusion. It may also be done if you have conditions like kidney disease, diabetes, or certain medications that affect magnesium balance.

What to Expect Before the Test

No special preparation is usually needed, but you may be asked to fast for 8–12 hours before the test if it involves drawing blood. If you’re taking certain medications (like some antibiotics, diuretics, or antacids), let your provider know.

What Happens During the Test?

A healthcare professional will draw blood from a vein in your arm. You may feel a slight pinch, but it usually doesn’t cause discomfort. The blood sample is then sent to a lab for analysis.

What the Results Mean

Results are compared to a general reference range, but exact values can vary by lab. Low magnesium (hypomagnesemia) may indicate conditions like malnutrition, kidney problems, or certain medications. High magnesium (hypermagnesemia) is less common but can occur with kidney failure or overuse of magnesium supplements.

Reference range

Adult: 1.7-2.2 mg/dLN/A

Specimen: stool

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 long does it take to get my results?
Test results are typically available within 1–3 business days, depending on your lab’s processing time. Your provider will contact you once they’re ready to discuss them.
What causes low magnesium levels?
Low magnesium can result from poor diet (low intake of foods like nuts, leafy greens, or whole grains), kidney problems, vomiting/diarrhea, certain medications (like diuretics or antibiotics), or conditions like alcoholism.
What causes high magnesium levels?
High magnesium is rare but can occur with kidney failure, overuse of magnesium supplements, or certain medications (like some laxatives or antacids). Severe cases may also be linked to adrenal insufficiency or excessive vitamin D.
  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