Oxalate, Urine (Sendout)

Useful For:

• Monitoring therapy for kidney stones using 24-hour urine collections

• Identifying increased urinary oxalate as a risk factor for stone formation

• Diagnosis of primary or secondary hyperoxaluria

Patient Preparation: Patients should avoid large doses (>2 g orally/24 hours) of Vitamin C for 24 hrs prior to and during collection.

Ordering Note: A timed 24-hour urine collection is the preferred specimen for measuring and interpreting this urinary analyte. Random collections normalized to urinary creatinine may be of some clinical use in patients who cannot collect a 24-hour specimen, typically small children. Random samples will be reported under Reference Laboratory Test 1 (SEND1). Timed samples with a collection interval of <22 hours or >26 hours will be rejected by Mayo Clinic Laboratories for the 24-hr test and run as Oxalate, Random, Urine.

Collect urine for 24 hours in a timed urine collection container with no metal cap or glued insert.

• Preferred: Add 5 mL of diazolidinyl urea (Germall, Mayo T822) as a preservative at start of collection. Specimens without preservative are acceptable if they are refrigerated during and after collection.
• 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.
• Mayo Urine Preservatives-Collection and Transportation for 24-Hour Urine Specimens
• Note: The addition of preservative must occur at the start of collection or application of temperature controls must occur during and after collection. All specimens will be evaluated at Mayo Clinic Laboratories for test suitability.

Mayo Preservative Supply: Diazolidinyl Urea (Germall) 5.0 mL [T822]

Note: Timed samples with a collection interval of <22 hours or >26 hours will be rejected by Mayo Clinic Laboratories for the 24-hr test and run as a random.

Outside Laboratories:

• Mix urine well and measure the volume. Record the total volume and collection interval (required).
• Transfer 10 mL urine to a screw-cap plastic aliquot. Refrigerate while awaiting shipment. Transport with a cold pack.

Stability: Refrigerated (preferred): 14 days; Frozen: 14 days, Ambient: 72 hours.

Reject Due To: Collected with preservative other than Diazolidinyl Urea. If collected without preservative, refrigerate during and after collection. Timed samples with a collection interval of <22 hours or >26 hours will be rejected by Mayo Clinic Laboratories for the 24-hr test and run as a random.

Processing:

• Mix urine well. Measure and record the total volume. Document the collection interval and total volume on the requisition.
• Transfer 10 mL urine to a screw-cap plastic aliquot. Refrigerate urine.

Result at Entry:

• ROXINT (Interval): <Enter the collection interval in hours>
• ROXLTV (Total Volume): <Enter the total volume in mL>

Sendouts:

• Order Mayo Test code: OXU
• Interfaced: Yes [Interface: 601; Worksheet: MARF]
• For random samples, batch the order to MayoAccess, add test code ROXUR, and delete test code OXU. CAST will add the SEND1 upon result receipt.

Stability: Refrigerated (preferred): 14 days; Frozen: 14 days, Ambient: 72 hours.

Reject Due To: Collected with preservative other than Diazolidinyl Urea. If collected without preservative, refrigerate during and after collection. Timed samples with a collection interval of <22 hours or >26 hours will be rejected by Mayo Clinic Laboratories for the 24-hr test and run as a random.