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HelpTest Code OXALU Oxalate, 24 Hour, Urine
Reporting Name
Oxalate, 24 Hr, UUseful For
Monitoring therapy for kidney stones
Identifying increased urinary oxalate as a risk factor for stone formation
Diagnosis of primary or secondary hyperoxaluria
Performing Laboratory
Mayo Clinic Laboratories in Rochester
Specimen Type
UrineNecessary Information
24-Hour volume is required.
Specimen Required
Patient Preparation: Avoid taking large doses (>2 g orally/24 hours) of vitamin C during specimen collection.
Supplies:
-Diazolidinyl Urea (Germall) 5.0 mL (T822)
-Aliquot Tube, 5 mL (T465)
Container/Tube: Plastic tube or a clean, plastic aliquot container with no metal cap or glued insert
Specimen Volume: 4 mL
Collection Instructions:
1. Add 5 mL of diazolidinyl urea (Germall) as a preservative at start of collection or refrigerate specimen during and after collection.
2. Collect urine for 24 hours.
3. Specimen pH should be between 4.5 and 8 and will stay in this range if kept refrigerated. Specimens with pH >8 may indicate bacterial contamination, and testing will be cancelled. Do not attempt to adjust pH as it will adversely affect results.
Additional Information: See Urine Preservatives-Collection and Transportation for 24-Hour Urine Specimens in Special Instructions for multiple collections.
Specimen Minimum Volume
1 mL
Testing Algorithm
See Hyperoxaluria Diagnostic Algorithm in Special Instructions.
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Urine | Refrigerated (preferred) | 14 days | |
| Frozen | 14 days |
Special Instructions
Reference Values
0.11-0.46 mmol/24 hours
9.7-40.5 mg/24 hours
The reference value is for a 24-hour collection. Specimens collected for other than a 24-hour time period are reported in unit of mmol/L for which reference values are not established.
Reference values have not been established for patients who are less than 16 years of age.
Day(s) and Time(s) Performed
Monday through Saturday
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 U.S. Food and Drug Administration.CPT Code Information
83945
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| OXU | Oxalate, 24 Hr, U | 14862-7 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| OCATE | Oxalate, 24 Hr, U (mmol/24 hr) | 14862-7 |
| OXU1 | Oxalate, 24 Hr, U (mg/24 hr) | 2701-1 |
| TM17 | Collection Duration | 13362-9 |
| VL15 | Urine Volume | 3167-4 |
Clinical Reference
1. Wilson DM, Liedtke RR: Modified enzyme-based colorimetric assay of urinary and plasma oxalate with improved sensitivity and no ascorbate interference: reference values and sample handling procedures. Clin Chem. 1991;37:1229-1235
2. Lieske JC, Wang X: Heritable traits that contribute to nephrolithiasis. Urolithiasis. 2019 Feb;47(1):5-10
3. Lieske JC, Turner ST, Edeh SN, Smith JA, Kardia SLR: Heritability of urinary traits that contribute to nephrolithiasis. Clin J Am Soc Nephrol. 2014 May;9(5):943-950
4. Zhao F, Bergstralh EJ, Mehta, RA, et al: Predictors of incident ESRD among patients with primary hyperoxaluria presenting prior to kidney failure. Clin J Am Soc Nephrol. 2016 Jan 7;11(1):119-126
Method Description
The assay utilizes oxalate oxidase, which oxidizes oxalate to carbon dioxide and peroxide. In the presence of peroxidase, the peroxide oxidatively couples 3-methyl-2-benzothiazolinone and 3-dimethylaminobenzoic acid to form indamine dye, which is measured spectrophotometrically at 580 nm.(Kasidas GP, Rose GA: Continuous-flow assay for urinary oxalate using immobilized oxalate oxidase. Ann Clin Biochem 1985;22:412-419; package insert: Oxalate kit. Trinity Biotech; V 07/2016)
Analytic Time
3 daysReject Due To
All specimens will be evaluated at Mayo Clinic Laboratories for test suitability.Method Name
Enzymatic
Forms
If not ordering electronically, complete, print, and send a Renal Diagnostics Test Request (T830) with the specimen.