Serum or Plasma Mass Concentration of Magnesium
A blood test to measure the amount of magnesium, a mineral essential for many bodily functions, including muscle and nerve function.
["Helps assess magnesium balance and identify potential deficiencies or excesses."]
Key facts at a glance
- LOINC
- 44601-3
- Short code
- M-IgM Ser Ql IFE
- Synonyms
- M-IgM 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 This Test Matters
Magnesium is crucial for muscle relaxation, nerve signaling, and maintaining normal heart rhythms. Low levels may cause muscle cramps, weakness, or irregular heartbeat, while high levels can lead to nausea, confusion, or weakness. This test helps doctors diagnose conditions like hypomagnesemia (low magnesium) or hypermagnesiumemia (high magnesium).
What to Expect Before the Test
No special preparation is usually needed, but you may be asked to fast for a few hours before the draw if your doctor specifies it. Wear comfortable clothing and avoid eating or drinking (except water) for 8–12 hours prior if fasting is required. Bring any medications you’re currently taking to your appointment.
How the Test Works
A blood sample is taken from a vein in your arm. The sample is sent to a lab where magnesium levels are measured using a specialized analytical method. Results are compared to reference ranges to determine if your levels are within normal limits.
Common Conditions Monitored
This test is often used to diagnose or monitor conditions such as chronic kidney disease, diarrhea, alcoholism, or certain medications that may affect magnesium levels. It may also be checked in patients with symptoms like muscle spasms, seizures, or irregular heartbeat.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Low magnesium levels (hypomagnesemia) can disrupt nerve and muscle function, weaken bones, and increase the risk of heart rhythm problems. High levels (hypermagnesiumemia) may cause weakness, confusion, or slowed breathing, particularly in severe cases. Doctors use these results to guide treatment, such as dietary adjustments, supplements, or medical interventions.
Short name
Magnesium Level
Frequently asked questions
Will I feel any pain during the blood draw?
Can I eat or drink normally before this test?
What if my magnesium level is outside the normal range?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
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.
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