Magnesium, 24 Hour Urine with Creatinine
Use
The test measures the amount of magnesium excreted in a 24‑hour urine collection, normalized to creatinine, to evaluate magnesium metabolism. It helps assess renal handling of magnesium, nutritional status, and can aid in diagnosing disorders such as hypomagnesemia, hypermagnesemia, and related metabolic or renal dysfunction.
Special Instructions
Collect a full 24‑hour urine specimen with acid preservative (25 mL 6 N HCl) to maintain pH below 3. Refrigerate during collection; mix and record total volume on the specimen container; send a 10 mL aliquot in a screw‑capped urine cup.
Limitations
Accuracy depends on complete collection of the 24‑hour urine pool, proper acid preservation, refrigeration during collection, and accurate volume recording. Incomplete collection, improper preservation or temperature control, or failure to note total volume can lead to inaccurate results.
Methodology
Mass Spectrometry
Biomarkers
LOINC Codes
- 3167-4
- 24447-5
- 44336-6
- 2162-6
Result Turnaround Time
Not provided.
Related Documents
For more information, please review the documents below
Specimen
Urine
Volume
10 mL aliquot
Minimum Volume
1.0 mL
Container
Screw‑capped urine cup
Collection Instructions
24‑hour urine with 25 mL 6 N HCl to maintain pH < 3; refrigerate during collection; mix and record total volume; send 10 mL aliquot.
Storage Instructions
Keep urine refrigerated during collection
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 4 days |
| Refrigerated | 7 days |
| Frozen | 90 days |