Magnesium, Urine
Use
Magnesium excretion controls magnesium balance.1 Magnesium urinary excretion is enhanced by increasing blood alcohol levels, diuretics, Bartter syndrome, corticosteroids, cis-platinum therapy and aldosterone. Renal magnesium wasting occurs in renal transplant recipients who are on cyclosporine and prednisone.2 Renal conservation of magnesium is diminished by hypercalciuria, salt-losing conditions, and the syndrome of inappropriate secretion of antidiuretic hormone.1 Magnesium deficiency is often inadequately documented by serum magnesium levels. Urinary magnesium analyses have been advocated before and after therapeutic magnesium administration to further investigate the significance of an apparent low serum magnesium.3
Special Instructions
The test request form must state the 24-hour collection volume. After collection, adjust pH to 1.5 to 2.0 with 6N HCl to preserve the sample's integrity. Proper labeling and timely transportation to the lab are essential to avoid sample rejection or degradation.
Limitations
The test may be affected by improper collection or transportation of the urine sample. The presence of blood in the urine, absence of preservative in the collection container, or improper labeling can lead to sample rejection. In addition, factors such as hypercalcemia, hypophosphatemia, and acidosis can interfere with the tubular reabsorption of magnesium, potentially impacting the results.
Methodology
Other
Biomarkers
LOINC Codes
- 19124-7
- 19124-7
- 24447-5
Result Turnaround Time
1-3 days
Related Documents
For more information, please review the documents below
Specimen
Urine
Volume
5 mL
Minimum Volume
2.2 mL
Container
Plastic urine container with 30 mL 6N HCl
Collection Instructions
Instruct the patient to void at 8 AM and discard the specimen. Then collect all urine including the final specimen voided at the end of the 24-hour collection period (ie, 8 AM the next morning). Screw the lid on securely. Transport the specimen promptly to the laboratory. Container must be labeled with patient's full name, room number, date and time collection started, and date and time collection finished.
Storage Instructions
Room temperature (KBS tablet is acceptable)
Causes for Rejection
No preservative in the collection container; presence of blood in the urine; improper labeling
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 14 days |
| Refrigerated | 14 days |
| Frozen | 14 days |