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Serum Magnesium Concentration (Qualitative Screening)

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

This test measures the amount of magnesium in your blood serum to check for imbalances that could affect muscle, nerve function, or other health conditions.

Quick summary

["Magnesium levels in your blood can signal potential health concerns that may require further evaluation."]

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

Key facts at a glance

LOINC
44597-3
Short code
M-IgG Ser Ql IFE
Synonyms
M-IgG Ser Ql IFE
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
immunofixation
CPT
82784
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 low or high magnesium levels. It may also be part of routine testing for certain conditions or before certain treatments.

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 it involves drawing blood from a vein. Avoid taking magnesium supplements or certain medications for a few days before testing.

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 brief pinch, but it usually doesn’t cause discomfort. The blood sample is then sent to a lab for analysis.

What Does the Test Result Mean?

Results are qualitative (yes/no) rather than a specific number, so they indicate whether your magnesium level is outside the expected range. Your provider will discuss the findings with you and may recommend follow-up testing or adjustments to your care plan.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Serum Mg (Qualitative)

Frequently asked questions

What causes low magnesium levels?
Low magnesium levels can result from poor diet (low intake of foods like nuts, leafy greens, or whole grains), certain medications, chronic kidney disease, vomiting or diarrhea, alcohol misuse, or conditions like diabetes or hyperthyroidism. If you suspect this may apply to you, discuss it with your healthcare provider.
What are common symptoms of magnesium imbalance?
Symptoms of low magnesium may include muscle twitches, cramps, spasms, weakness, irregular heartbeat, numbness, or fatigue. High magnesium levels are less common but can cause nausea, low blood pressure, or confusion. If you experience these symptoms, see your provider for evaluation.
Can magnesium levels change over time?
Yes, magnesium levels can fluctuate due to diet, medications, illness, or stress. Regular monitoring may be needed if you have conditions like kidney disease, heart problems, or are taking certain medications that affect magnesium metabolism.
  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