Test Details

Mnemonic

OXA

Ordering Code

3508310

CPT-4 Code(s)

83945

Specimen Information

Patient Preparation

Patient should be fasting for at least 12 hours prior to collection. Patient should avoid taking
vitamin C supplements for 24 hours prior to collection.

Collect

Green sodium heparin

Specimen Preparation

After drawing specimen, immediately place green sodium heparin tube on wet ice. Centrifuge
for 10 minutes 3500 rpm within 1 hour of collection. Use of a 4 degree °C refrigerated centrifuge
is optimal but not required. Aliquot 5.0 mL plasma in screw capped plastic vial. 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. CRITICAL FROZEN.

Alternate Specimen

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.
Rejection Criteria

Minimum Volume

2.0 mL

Transport Temperature

Critical frozen

Rejection Criteria

Sample collected in anything other than a green sodium heparin.

Stability

Room temperature: Unacceptable
Refrigerated: Unacceptable
Frozen: 30 days

Methodology

Enzymatic
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Reference Range

≤ 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.
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Performing Laboratory

MAYO Clinic Laboratories
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New York DOH Approval Status

Yes
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