Serine Proteinase 3 (PR3) Antibody

Ordering Recommendation

When used in conjunction with other autoantibody tests (ANCA, MPO), may aid in differentiating suspected Wegener granulomatosis (WG) from other vasculitides. May be useful to monitor patients with PR3 antibodies.

Panel tests are available. For the workup of suspected vasculitis, refer to ANCA-Associated Vasculitis Profile (ANCA/MPO/PR3) (3003745). For patients with a history of vasculitis, refer to Myeloperoxidase (MPO) Antibody and Serine Proteinase 3 (PR3) Antibody with Reflex to Anti-Neutrophil Cytoplasmic Antibody, IgG by IFA (3003746).

Mnemonic

PR3

Performed

Mon-Sat

Methodology

Semi-Quantitative Multiplex Bead Assay

Reported

1-2 Days

New York DOH Approval Status

This test is New York DOH approved.

Specimen Required

Patient Preparation:

Collect:

Serum separator tube.

Specimen Preparation:

Separate serum from cells ASAP or within 2 hours of collection. Transfer 1 mL serum to a Standard Transport Tube. (Min: 0.2 mL)

Storage/Transport Temperature:

Refrigerated.

Unacceptable Conditions:

Plasma, urine, or other body fluids. Contaminated, hemolyzed, or severely lipemic specimens., icteric, or lipemic specimens.

Remarks:

Stability:

After separation from cells: Ambient: 48 hours; Refrigerated: 2 weeks; Frozen: 1 year (avoid repeated freeze/thaw cycles)

Reference Interval

19 AU/mL or less

Negative

20-25 AU/mL

26 AU/mL or greater

Equivocal

Positive

Interpretive Data

Approximately 85% of patients with a C-ANCA pattern by IFA have antibodies specific for PR3.