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Test Code POXA1 Oxalate, Plasma

Test Down Notes

This test is temporarily unavailable. For additional details, see the test announcement here.


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)

Disease States

  • Hyperoxaluria

Special Instructions

Reporting Name

Oxalate, Plasma

Specimen Type

Plasma Na Heparin

Specimen Minimum Volume

2 mL

Specimen Stability Information

Specimen Type Temperature Time
Plasma Na Heparin Frozen 30 days

Reject Due To

  All specimens will be evaluated at Mayo Clinic Laboratories for test suitability.

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.

Supportive Data

A difference in plasma oxalate results between the previous and current methods was observed; Overall the new results were 2.5% higher by Bland-Altman analysis (2.5%, y=0.7284x + 2.0093, R[2] = 0.9537). However, the new method detected significantly lower results for samples with a plasma oxalate concentration greater than 20 mcmol/L (Bland-Altman bias =-25.6%).

Day(s) Performed

Monday through Friday

Report Available

3 to 7 days

Specimen Retention Time

2 weeks

Performing Laboratory

Mayo Clinic Laboratories in Rochester

CPT Code Information

83945

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

Forms

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