Magnesium, Feces
Use
Workup of cases of chronic diarrhea. Identifying the use of magnesium-containing laxatives contributing to osmotic diarrhea. Measurement of magnesium in liquid stool can assist in identifying intentional or inadvertent use of magnesium‑ and/or phosphate‑containing laxatives as the cause. Osmotic diarrhea is suggested when the osmotic gap is above 75 mOsm/kg and magnesium concentration is above 110 mg/dL. ([mayocliniclabs.com](https://www.mayocliniclabs.com/test-catalog/overview/606756?utm_source=openai))
Special Instructions
This test is only clinically valid if performed on watery specimens. In the event a formed fecal specimen is submitted, the test will not be performed. Patient Preparation: No barium, laxatives, or enemas may be used for 96 hours prior to start of, or during, collection. ([mayocliniclabs.com](https://www.mayocliniclabs.com/test-catalog/overview/606756?utm_source=openai))
Limitations
In very rare cases, gammopathy, in particular type IgM (Waldenstrom macroglobulinemia), may cause unreliable results. ([mayocliniclabs.com](https://www.mayocliniclabs.com/test-catalog/overview/606756?utm_source=openai))
New York Approved
Methodology
Other
Biomarkers
LOINC Codes
- 29911-5
- 29911-5
Result Turnaround Time
1-3 days
Related Documents
For more information, please review the documents below
Specimen
Stool
Volume
10 g
Minimum Volume
5 g
Container
Stool container
Collection Instructions
Collect a very liquid stool specimen.
Patient Preparation
No barium, laxatives, or enemas may be used for 96 hours prior to start of, or during, collection.
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | Ambient: 48 hours |
| Refrigerated | Refrigerated: 7 days |
| Frozen | Frozen (preferred): 14 days |