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RNP Antibody

Anti-RNP

Test Codes

EPIC: LAB6991, Beaker: RNPA

Department

Special Chemistry

Specimen Collection Criteria

Collect: One Gold-top SST tube. (Minimum Whole Blood: 4.0 mL)

Physician Office/Draw Specimen Preparation

Let specimen clot 30-60 minutes then immediately centrifuge to separate serum from cells. Refrigerate (2-8°C or 36-46°F) the centrifuged collection tube within two hours of collection. (Minimum Serum: 1.0 mL)

Preparation for Courier Transport

Transport: Centrifuged collection tube, refrigerated (2-8 °C or 36-46 °F). (Minimum Serum: 1.0 mL)

Rejection Criteria

• Plasma specimens.
• Heat-inactivated specimens.
• Severely lipemic or hemolyzed specimens.

In-Lab Processing

Let specimen clot 30-60 minutes then immediately centrifuge to separate serum from cells. Room temperature is acceptable for a maximum of two hours. (Minimum Serum: 1.0 mL)

Storage

Specimen Stability for Testing:

Centrifuged SST Tubes and Microtainers^® with Separator Gels
Room Temperature (20-26°C or 68-78.8°F): 2 hours
Refrigerated (2-8°C or 36-46°F): 7 days
Frozen (-20°C/-4°F or below): Unacceptable

Red-top Tubes and Microtainers^® without Separator Gels
Room Temperature (20-26°C or 68-78.8°F): 2 hours
Refrigerated (2-8°C or 36-46°F): Unacceptable
Frozen (-20°C/-4°F or below): Unacceptable

Serum Specimens (Pour-Overs)
Room Temperature (20-26°C or 68-78.8°F): 2 hours
Refrigerated (2-8°C or 36-46°F): 7 days
Frozen (-20°C/-4°F or below): 2 months

Specimen Storage in Department Prior to Disposal:

Refrigerated (2-8°C or 36-46°F): 7 days

Laboratory

Royal Oak Special Testing Laboratory

Performed

Monday, Wednesday, Friday.
Results available within 2 business days.

Reference Range

Negative:  < 1.0 U
Equivocal:  NA
Positive:  ≥ 1.0 U

Test Methodology

Multiplex Flow Assay.

Interpretation

When found in isolation (i.e. Smith and double-stranded DNA antibodies are not detected), a positive result for RNP antibodies is consistent with the diagnosis of mixed connective tissue disorder (MCTD).

Clinical Utility

RNP is a small nuclear ribonucleoprotein that contains 3 protein autoantibodies (called A, C, and 68 kD). RNP antibodies are detected in approximately 50% of patients with lupus erythematosus and in patients with other connective tissue disorders, most notably mixed connective tissue disease (MCTD). MCTD is characterized by high levels of RNP antibodies without detectable Smith or double-stranded DNA antibodies. Testing for RNP antibodies is not useful in patients negative for antinuclear antibodies.

CPT Codes

86235
LOINC: 23929-3

Contacts

Last Updated

2/10/2024