Magnesium, 24-hour Urine-994
Test info
Magnesium excretion controls magnesium balance. 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. Renal conservation of magnesium is diminished by hypercalciuria, salt-losing conditions, and the syndrome of inappropriate secretion of antidiuretic hormone. 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.
Specimen
(Note: This volume does not allow for repeat testing.)
- Measure and record the 24-hour total volume
- Mix well
- Transfer a 5 mL aliquot to a Transfer vial/tube with cap - 12mL (LabCorp)
- Total volume
Ambient (preferred) - 14 days
Refrigerated - 14 days
Frozen - 14 days
Freeze/thaw cycles - Stable x3
- No preservative in the collection container
- Presence of blood in the urine
- Visibly bloody specimen
Performance
Atomic absorption spectrometry (AAS) or colorimetric
Clinical and Interpretive info
Environmental exposure: 12.0 − 293.0 mg/24 hours