Blood magnesium
magnesium test · serum magnesium · blood magnesium level
This is a blood test from a vein. It shows your magnesium level. Your muscles, nerves, and heart need magnesium.
For cramps, skipped heartbeats, weakness, while taking water pills, or with kidney or bowel disease.
⏱ Duration: the blood draw takes a few minutes; results usually come the next day
Be sure to tell your doctor
How to prepare
- Food. Usually fasting: no food for 8 to 12 hours. Plain water is fine. Check with the lab.
- The day before. For 24 hours, no alcohol and no hard workouts. Best not to smoke in the morning.
- Medicines. Do not stop them on your own. Tell your doctor what you take. They will decide if anything should change.
What to bring
- Your test request form
- Your ID
How it goes
- You sit down and rest your arm on the armrest
- A band is tightened above your elbow
- The skin is wiped with antiseptic
- A quick prick, and blood fills a tube
- The needle comes out, and a cotton pad is pressed on the spot
What you'll feel
- A quick prick, like a pinch
- Sometimes slight dizziness. Tell the nurse
Afterwards
- Press the cotton pad for 3 to 5 minutes and keep your arm straight
- You can eat right away and go back to your usual day
- Results usually come in 1 day. The lab will tell you when
Common questions
If my magnesium is normal, do I have enough?
Usually yes. But only a small part of your magnesium is in the blood. So your doctor also looks at your symptoms.
Should I take magnesium before the test?
Do not change anything on your own. Tell your doctor what you take. They will decide.