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Magnesium, Whole Blood 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. Magnesium helps with muscle and nerve function, blood pressure regulation, and energy production.

Quick summary

["Magnesium levels can affect muscle cramps, nerve function, and overall health—check your results with your doctor."]

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

Key facts at a glance

LOINC
17235-3
Short code
Magnesium WBC-sCnc
Synonyms
Magnesium WBC-sCnc
Category
electrolyte
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
1.7
Ref high
2.2
Critical range
2 N/A – 30 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
83735
SNOMED
900000000000003002
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 conditions like low magnesium (hypomagnesemia) or high magnesium (hypermagnesium). It can also be part of routine blood work or monitoring for certain medical conditions.

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’s part of a metabolic panel. Bring any medications or supplements you’re taking, as they may affect results.

What Happens During the Test?

A healthcare professional will draw blood from a vein in your arm using a small needle. You may feel a slight pinch, but the process usually takes just a few minutes. The blood sample is then sent to a lab for analysis.

What Do the Results Mean?

Results are compared to a reference range, but exact values can vary by lab. Low magnesium may cause muscle spasms or heart rhythm issues, while very high levels can weaken your bones or affect kidney function. Always discuss results with your doctor.

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.

◆Associated findings1

Short name

Magnesium Level (Blood)

Frequently asked questions

What causes low magnesium levels?
Low magnesium can result from poor diet (low intake of foods like nuts, leafy greens, or whole grains), certain medications (like diuretics or antibiotics), chronic vomiting/diarrhea, kidney problems, or alcohol misuse. Some health conditions, like diabetes or Crohn’s disease, may also affect magnesium balance.
What causes high magnesium levels?
High magnesium levels are less common but can occur with kidney failure (since kidneys usually filter excess magnesium), severe dehydration, or overuse of magnesium supplements. Rarely, certain medications or genetic conditions may also contribute.
Can magnesium levels change with diet?
Yes! Foods rich in magnesium (spinach, almonds, black beans, avocados, and fortified cereals) can naturally boost levels. However, excessive intake from supplements or processed foods (like soda) may lead to imbalances. Always balance diet with medical advice.
  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