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Test Code 1924 Oxalate, 24 Hour, Urine

Additional Codes

Mayo Test ID

Reporting Name

Oxalate, U

Useful 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 Medical Laboratories in Rochester

Specimen Type


Specimen Required

Container/Tube: Plastic, 5-mL urine tube (T465) or a clean, plastic aliquot container with no metal cap or glued insert

Specimen Volume: 4 mL

Collection Instructions:

1. Add 30 mL of toluene as 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:

1. 24-Hour volume is required.

2. Avoid taking large doses (>2 g orally/24 hours) of vitamin C during specimen collection.

3. See Urine Preservatives-Collection and Transportation for 24-Hour Urine Specimens in Special Instructions for multiple collections.

Barnes-Jewish Hospital Note:
Submit an entire 24-hour urine collection in a plain, brown urine container.

Additional Information:

1. Starting and ending times of collection are required.
2. Follow instructions for Urine Collection in Special Instructions.

3. Urine timed measurement is performed at an additional charge per 24-hour collection (CPT Code-81050).

Specimen Minimum Volume

1 mL

Specimen Stability Information

Specimen Type Temperature Time
Urine Refrigerated (preferred) 14 days
  Frozen  14 days

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.

Day(s) and Time(s) Performed

Monday through Saturday

Test Classification

This test was developed and its performance characteristics 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


LOINC Code Information

Test ID Test Order Name Order LOINC Value
OXU Oxalate, U In Process


Result ID Test Result Name Result LOINC Value
OCATE Oxalate, U 14862-7
OXU1 Oxalate, U 2701-1
TM17 Collection Duration 13362-9
VL15 Urine Volume 3167-4
OX_A Ox Conc (mmol/L) 34349-1
OXCN2 Oxalate Concentration 27222-9

Testing Algorithm

See Hyperoxaluria Diagnostic Algorithm in Special Instructions.

Method Name

Enzymatic Using Oxalate Oxidase

Urine Preservative Collection Options







6N HCl


50% Acetic Acid








Boric Acid




Barnes-Jewish Hospital Additional Information:
For BJH Laboratory Use Only

Laboratory Processing Instructions:
BJH Chemistry will forward to the performing laboratory.