OXALATE, URINE - 24 HOUR

Specimen Required
Collect 24 hour urine, refrigerate during collection. See below for preferred 24 hour urine collection instructions. Send 25.0 mL preserved urine (10.0 mL minimum) refrigerated in a screw-capped plastic urine container. Record total volume on test requisition and specimen label.
24 hour urine collection (preferred): The bladder must be emptied at the time the collection is to begin, and this urine is discarded. Thereafter all urine must be collected until the end of the scheduled time.
Collect urine with 25 mL of 6N HCl at start of collection to maintain pH between 1 and 3. Refrigerate urine during collection (critical). Mix the collection well before removing aliquot.
NOTE: Patients should refrain from Vitamin C supplements during and for 48 hours prior to urine collection for oxalate.

Alternate Specimen
Alternate method of collection for 24 hour. Refrigerate urine during collection (critical) and add 25 mL of 6N HCl to the entire collection within 4 hours of completing. Mix the collection well before checking the pH. Ensure pH is between 1-3. Record total volume on test request and on container label. Send 25 mL aliquot (10.0 mL minimum) refrigerated in a screw-capped plastic urine container.
Alternate method of collection for time urine sample: Requirements are the same as for 24 hour collection.

Rejection Criteria
pH other than 1-3

Methodology
Spectrophotometry

Stability
Room Temperature: Unacceptable; Refrigerated: 7 days; Frozen: 7 days

Reference Range
Males: 0-45 mg/24 hours
Females: 0-42 mg/24 hours
Urine Creatinine:
Males:   1.0-2.0 g/24 hours  
Females:   0.8-1.8 g/24 hours  
No reference ranges available for timed or random samples

Performed
Monday, Wednesday, Friday

Turnaround Time4 days
Test CodeUOX24
CPT-4 Code (s)
83945, 82570
LOINC Codes
Oxalate   2701-1  
Creatinine   2162-6  
Total volume   19153-6  

Warde
Medical
Laboratory