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Test Code Oxalate Oxalate, Plasma

Reporting Name

Oxalate, P

Useful For

Assessing the body pool size of oxalate. The settings in which it has been most useful include patients with enzyme deficiencies, such as primary hyperoxaluria, which result in overproduction of oxalate or patients with enteric hyperoxaluria (EH).

 

In the presence of chronic kidney disease (CKD), 3 uses of plasma oxalate are:

 

-If primary hyperoxaluria (PH) is suspected in a patient with CKD of indeterminate cause, and urinary oxalate is not available, plasma oxalate can be used to aid in diagnosis. However although  plasma oxalate levels are markedly elevated in PH patients with CKD suggesting the diagnosis, ancillary tests often are necessary to confirm it, such as genetic analysis of the 3 causative genes, or pathologic demonstration of oxalate crystals in tissues

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

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


Specimen Required


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

 

Patient Preparation:

1. Fasting (12 hours)

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

Specimen Type: Acidified plasma

Collection Container/Tube: Green top (sodium heparin)

Submission Container/Tube: Plastic vial

Specimen Volume: 5 mL

Collection Instructions:

1. Place on wet ice immediately.

2. Centrifuge for 10 minutes at 3,500 rpm at 4° C within 1 hour of draw.

3. Adjust the pH of the plasma specimen to a pH of 1 to 3.5 (ideal range is 2.3-2.7) with approximately 10 mcL concentrated (12N) HCl per 1 mL plasma.

Additional Information: Nonacidified specimen can be accepted if the heparinized plasma is properly frozen. However, a disclaimer will be added in nonacidified plasma, oxalate values may increase spontaneously (average 50% increase for plasma oxalate <15 mcmol/L; average 10% increase for plasma oxalate >15 mcmol/L).


Seattle Children's Hospital Note:

Collection: 5 mL in a Green Top tube, deliver to lab ON WET ICE.

Processing:

CPA: Promptly spin at 3500 rpm for 10 minutes at 4° C within 1 hour of draw, aliquot at least 2 mL plasma and immediately deliver to Core.

Core:  pH to 1 to 3.5 (ideal range is 2.3-2.7) with approximately 10 mcL concentrated (12N) HCL per 1mL plasma.  Freeze ASAP.

Specimen Type

Plasma Na Heparin

Specimen Minimum Volume

2 mL

Specimen Stability Information

Specimen Type Temperature Time
Plasma Na Heparin Frozen 14 days

Day(s) and Time(s) Performed

Monday through Friday; 6 a.m.-8 p.m.

Performing Laboratory

Mayo Medical Laboratories in Rochester

Method Name

Ion Chromatography (IC)

Method Description

This is an ion-exchange chromatography (or ion chromatography) method which allows the separation of ions and polar molecules based on their affinity to the ion exchanger. The oxalate molecule will be separated from other anions using the Dionex ICS 2100 instrument.(Unpublished Mayo method)

Reference Values

<1.6 mcmol/L

Reference values have not been established for patients under 21 and greater than 81 years of age.

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

83945

LOINC Code Information

Test ID Test Order Name Order LOINC Value
POXA Oxalate, P 15085-4

 

Result ID Test Result Name Result LOINC Value
POXA Oxalate, P 15085-4

Special Instructions

Reject Due To

Hemolysis

NA

Lipemia

NA

Icterus

NA

Other

Nonheparinized specimen

Testing Algorithm

See Hyperoxaluria Diagnostic Algorithm in Special Instructions.