Test Code MAGU Magnesium, 24 Hour, Urine
Useful For
Assessing the cause of abnormal serum magnesium concentrations
Determining whether nutritional magnesium loads are adequate
Calculating urinary calcium oxalate and calcium phosphate supersaturation and assessing kidney stone risk
Special Instructions
Method Name
Colorimetric Endpoint Assay
Reporting Name
Magnesium, 24 Hr, USpecimen Type
UrineSpecimen Required
Collection Container/Tube: 24-hour graduated urine container with no metal cap or glued insert
Submission Container/Tube: Plastic, 5-mL tube (T465) or a clean, plastic urine container with no metal cap or glued insert
Specimen Volume: 4 mL
Collection Instructions:
1. Collect urine for 24 hours.
2. Refrigerate specimen within 4 hours of completion of 24-hour collection.
Additional Information:
1. 24-Hour volume is required.
2. See Urine Preservatives-Collection and Transportation for 24-Hour Urine Specimens in Special Instructions for multiple collections.
Specimen Minimum Volume
1 mL
Specimen Stability Information
Specimen Type | Temperature | Time | Special Container |
---|---|---|---|
Urine | Refrigerated (preferred) | 14 days | |
Frozen | 14 days | ||
Ambient | 72 hours |
Reject Due To
All specimens will be evaluated at Mayo Clinic Laboratories for test suitability. |
Reference Values
51-269 mg/24 hr
Reference values have not been established for patients <18 years and >83 years of age.
Reference values apply to 24-hour collections.
Day(s) and Time(s) Performed
Monday through Sunday; Continuously
Performing Laboratory

Test Classification
This test has been modified from the manufacturer’s instructions. Its performance characteristics were determined by Mayo Clinic in a manner consistent with CLIA requirements.CPT Code Information
83735
LOINC Code Information
Test ID | Test Order Name | Order LOINC Value |
---|---|---|
MAGU | Magnesium, 24 Hr, U | 24447-5 |
Result ID | Test Result Name | Result LOINC Value |
---|---|---|
MG24 | Magnesium, 24 Hr, U | 24447-5 |
TM115 | Collection Duration | 13362-9 |
VL111 | Urine Volume | 3167-4 |
MGCN | Magnesium Concentration | 32024-2 |
Forms
If not ordering electronically, complete, print, and send a Renal Diagnostics Test Request (T830) with the specimen.