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Test ID POXA1 Oxalate, Plasma

Specimen Required

Any client who has never collected a specimen for this test should call 800-533-1710 or 507-266-5700 and ask for the Clinical Specialty Laboratory for more detailed instructions.


Patient Preparation:

1. Fasting (for a minimum of 12 hours)

2. Patient should avoid taking vitamin C supplements for 24 hours prior to collection.

Specimen Type: Acidified plasma

Collection Container/Tube: Green top (sodium heparin)

Submission Container/Tube: Plastic vial

Specimen Volume: 5 mL

Collection Instructions:

1. Place specimen on wet ice immediately.

2. Centrifuge for 10 minutes at 3500 rpm within 1 hour of collection. Use of a 4° C refrigerated centrifuge is optimal but not required.

3. Aliquot plasma into a plastic vial.

4. Adjust the pH of the plasma specimen to a pH of 2.3-2.7 with approximately 10 mcL concentrated (12M) hydrochloric acid (or 20 mcL of 6M HCl) per 1 mL plasma.

Additional Information: Nonacidified specimens can be accepted if the heparinized plasma is properly frozen. A disclaimer will be added in nonacidified plasma, "Sample was received nonacidified and frozen. In nonacidified samples oxalate values may increase spontaneously." Although there can be a small absolute increase of plasma oxalate in nonacidified specimens, this will not change the clinical interpretation.

Useful For

Assessing the body pool size of oxalate in patients with enzyme deficiencies, such as primary hyperoxaluria (PH), or patients with enteric hyperoxaluria


Aiding in the diagnosis of PH in a patient with chronic kidney disease of indeterminate cause when urinary oxalate is not available


Monitoring patients with renal failure and primary or enteric hyperoxaluria in order to be sure they are receiving enough dialysis


Aiding in maintaining plasma oxalate levels below supersaturation (25-30 mcmol/L)

Special Instructions

Method Name


Reporting Name

Oxalate, Plasma

Specimen Type

Plasma Na Heparin

Specimen Minimum Volume

2 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Plasma Na Heparin Frozen 30 days

Reference Values

≤2.0 mcmol/L

Reference values have not been established for patients younger than 18 years of age or older than 87 years of age.

Day(s) Performed

Monday through Friday

Report Available

3 to 7 days

Performing 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


LOINC Code Information

Test ID Test Order Name Order LOINC Value
POXA1 Oxalate, Plasma 15085-4


Result ID Test Result Name Result LOINC Value
POXA1 Oxalate, Plasma 15085-4


If not ordering electronically, complete, print, and send a Renal Diagnostics Test Request (T830) with the specimen.