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HelpTest Code OXCO1 Oxalate, Random, Urine
Specimen Required
Only orderable as part of a profile. For more information see ROXUR / Oxalate, Random, Urine.
Patient Preparation: Avoid taking large doses (>2 g orally/24 hours) of vitamin C prior to specimen collection.
Supplies: Urine Tubes, 10 mL tube (T068)
Container/Tube: 10-mL plastic tube or a clean, plastic container with no metal cap
Specimen Volume: 7 mL
Collection Instructions:
1. Collect a random urine specimen.
2. No preservative.
3. Specimen pH should be between 4.5 and 8 and will stay in this range if kept refrigerated. Specimens with pH above 8 may indicate bacterial contamination, and testing will be cancelled. Do not attempt to adjust pH as it will adversely affect results.Useful For
Monitoring therapy for kidney stones
Identifying increased urinary oxalate as a risk factor for stone formation
Diagnosis of primary or secondary hyperoxaluria
Method Name
Only orderable as part of a profile. For more information see ROXUR / Oxalate, Random, Urine.
Enzymatic Using Oxalate Oxidase
Reporting Name
Oxalate, Random, U (mmol/L)Specimen Type
UrineSpecimen 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.Clinical Information
Oxalate is an end product of glyoxalate and glycerate metabolism. Humans have no enzyme capable of degrading oxalate so it must be eliminated by the kidney.
In tubular fluid, oxalate can combine with calcium to form calcium oxalate stones. In addition, high concentrations of oxalate may be toxic for renal cells.
Increased urinary oxalate excretion results from inherited enzyme deficiencies (primary hyperoxaluria), gastrointestinal disorders associated with fat malabsorption (secondary hyperoxaluria), or increased oral intake of oxalate-rich foods or vitamin C.
Since increased urinary oxalate excretion promotes calcium oxalate stone formation, various strategies are employed to lower oxalate excretion.
Reference Values
Only orderable as part of a profile. For more information see ROXUR / Oxalate, Random, Urine.
No established reference values
Interpretation
An elevated urine oxalate (>0.46 mmol/day) may suggest disease states such as secondary hyperoxaluria (fat malabsorption), primary hyperoxaluria (alanine glyoxalate transferase enzyme deficiency, glyceric dehydrogenase deficiency), idiopathic hyperoxaluria, or excess dietary oxalate or vitamin C intake.
In stone-forming patients high urinary oxalate values, sometimes even in the upper limit of the normal range, are treated to reduce the risk of stone formation.
The urinary oxalate creatinine ratio varies widely in young children from <0.35 mmol/mL at birth, to <0.15 mmol/mL at 1 year, to <0.10 mmol/mL at 10 years, and <0.05 mmol/mL at 20 years of age (see table below).(1)
|
Oxalate/Creatinine (mg/mg) |
|
|
Age (year) |
95th Percentile |
|
0-0.5 |
<0.175 |
|
0.5-1 |
<0.139 |
|
1-2 |
<0.103 |
|
2-3 |
<0.08 |
|
3-5 |
<0.064 |
|
5-7 |
<0.056 |
|
7-17 |
<0.048 |
Cautions
Ingestion of ascorbic acid (>2 g/day) may falsely elevate the measured urinary oxalate excretion.
Day(s) Performed
Monday through Saturday
Report Available
3 daysPerforming Laboratory
Mayo Clinic Laboratories in Rochester
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. This test has not been cleared or approved by the US Food and Drug Administration.CPT Code Information
83945
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| OXCO1 | Oxalate, Random, U (mmol/L) | 15086-2 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| OXCO1 | Oxalate, Random, U (mmol/L) | 15086-2 |