What it measures
The magnesium in a whole blood sample, with the red cells left in. Red cells hold more magnesium than the serum around them, so the result covers both. It is a different measure from the usual serum magnesium test.
Why people test it
- Part of a mineral screen that reads several minerals in whole blood from one sample.
- Checked by people who want a reading that includes the magnesium inside red cells.
- Checked by people on medicines that can lower magnesium, such as long-term acid-reducing tablets.
Typical range
Ranges vary by lab, method, age and sex, and your report shows the lab's own range. Whole blood results run higher than serum results, so the two cannot be compared directly.
Finger-prick or vein?
Offered as a vein draw only, as a screen of several minerals needs more blood than a finger-prick gives.
Whole blood includes the magnesium inside red cells, but most of the body's magnesium sits in bone and muscle, so a blood test is still a limited measure.
