Skip to content

Serum Magnesium 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

["Magnesium helps with muscle and nerve function, blood pressure, and bone health."]

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

Key facts at a glance

LOINC
43190-8
Short code
MAG/SGPG IgM Titr Ser IA
Synonyms
MAG/SGPG IgM Titr Ser IA
Category
glucose
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
ia
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 Might You Need This Test?

Your doctor may order this test if you have symptoms like muscle cramps, weakness, or irregular heartbeat. It could also be part of routine check-ups, especially if you have conditions like kidney disease, diabetes, or heart problems. Some medications may also affect magnesium levels, so your doctor might monitor it if you’re taking them.

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. Drink plenty of water the day before to ensure proper blood flow. Avoid taking magnesium supplements unless directed by your doctor.

What Happens During the Test?

A healthcare provider will draw blood from a vein in your arm. The process is quick and typically painless. The blood sample is sent to a lab for analysis, where magnesium levels are measured using a specialized method.

What Do the Results Mean?

Results are compared to a standard range, but exact values can vary by lab. Low magnesium (hypomagnesemia) may cause muscle spasms or irregular heart rhythms, while high levels (hypermagnesium) could lead to weakness or slow heart rate. Your doctor will interpret results in the context of your overall health.

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?
Results are typically available within 1–3 business days, depending on your lab. Your doctor will contact you once they’re ready, so check with them for updates.
Can I eat or drink anything before the test?
If fasting is required, avoid food and liquids (except water) for 8–12 hours before the test. If no fasting is needed, eat and drink normally. Always follow your doctor’s instructions.
Will I feel any pain during the blood draw?
Most people experience only a slight pinch or discomfort during the blood draw. Some may feel a small bruise or soreness afterward, but it’s usually mild and temporary.
  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