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Proteinase 3 Autoantibodies

PR3, Serine Protease 3 Antibody

Test Codes

WARDE: PR3AB, EPIC: LAB6324, SOFT: XPR3

Department

Send Outs

Specimen Collection Criteria

Collect (preferred specimen): One Gold-top SST tube.
Also acceptable: One plain Red-top tube.

Send specimen for processing immediately after collection. 

Physician Office/Draw Specimen Preparation

Let specimen clot 30-60 minutes then centrifuge to separate serum from cells. Transfer serum to a plastic transport tube and freeze (-20°C/-4°F or below).

Preparation for Courier Transport

Transport: 1.0 mL serum, frozen (-20°C/-4°F or below). (Minimum: 0.1 mL)

Rejection Criteria

• Grossly hemolyzed specimens.
• Lipemic specimens.
• Specimens not collected and processed as indicated.

In-Lab Processing

Let specimen clot 30-60 minutes then centrifuge to separate serum from cells. Transfer serum to a plastic transport tube and freeze (-20°C/-4°F or below).

Transport: 1.0 mL serum, frozen (-20°C/-4°F or below). (Minimum: 0.1 mL)

Storage

Specimen Stability for Testing:

Room Temperature (20-26°C or 68-78.8°F): 8 hours
Refrigerated (2-8°C or 36-46°F): 48 hours
Frozen (-20°C/-4°F or below): 14 days

Specimen Storage in Department Prior to Disposal:

Specimen retention time is determined by the policy of the reference laboratory. Contact the Send Outs Laboratory with any questions.

Laboratory

Sent to Warde Medical Laboratory, Ann Arbor, MI.

Performed

Monday – Friday.
Results available in 2-4 days.

Reference Range

Negative: Less than 20 U.
Weakly Positive: 21-30 U.
Positive: Greater than 30 U.

Test Methodology

Enzyme Immunoassay.

Interpretation

A positive test for Anti-PR3 has a high positive value for Wegener's granulomatosis (WG); fewer that 2% of positive results occur in patients who do not have WG. The presence of Anti-PR3 is a specific diagnostic indicator of WG and is found in more than 80% of patients with active WG.

A negative result for Anti-PR3 diminishes the likelihood that a patient has active WG; but approximately 20% of patients with WG may test negative for Anti-PR3.

Clinical Utility

Useful for evaluating patients suspected of having Wegener's granulomatosis (WG).

CPT Codes

83516
LOINC:  46267-1

Contacts

Last Updated

7/13/2021