Cytosolic 5'-Nucleotidase 1A (cN-1A) Antibody (IgG)

Test Code

10266

CPT Codes
83516

Preferred Specimen

0.5 mL serum

Minimum Volume

0.3 mL

Other Acceptable Specimens

Plasma collected in: EDTA (lavender-top) tube

Transport Temperature

Room temperature

Specimen Stability

Room temperature: 7 days
Refrigerated: 14 days
Frozen: 28 days

Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)

Moderate to gross hemolysis

Methodology
Enzyme Linked Immunosorbent Immunoassay (ELISA)

FDA Status
This test was developed and its analytical performance characteristics have been determined by Quest Diagnostics. It has not been cleared or approved by FDA. This assay has been validated pursuant to the CLIA regulations and is used for clinical purposes.

Setup Schedule

Set up: Tues, Thurs, Sat; Report available: 3-6 days

Reference Range

<15 Units	Negative
15-19 Units	Borderline
≥20 Units	Positive

Clinical Significance

The cN-1A Ab assay is a useful aid for the diagnosis of inclusion body myositis (IBM). The analytical sensitivity of this assay is 35-70%, based on published reports [1, 2]. In our validation study with 120 healthy adult subjects, 1.7% had a positive cN-1A Ab result and 6.7% had an equivocal result. However, published reports and our own internal studies suggest that patients with Sjogren’s syndrome, systemic lupus erythematosus, dermatomyositis (DM), or polymyositis (PM), are significantly more likely to have a positive cN-1A Ab result [1, 2, 3]. In contrast, patients presenting clinically with IBM rarely produce autoantibodies associated with a diagnosis of DM or PM [3]. Therefore, cN-1A Ab results must be interpreted in context with other details of the patient’s clinical evaluation.

References
1. Larman HB, et al. Cytosolic 5'-nucleotidase 1A autoimmunity in sporadic inclusion body myositis. Ann Neurol. 2013 Mar;73(3):408-18.
2. Felice KJ, et al. Neuromuscul Disord. 2018 Aug;28(8):660-664
3. Kramp SL, et al. Auto Immun Highlights. 2016 Dec;7(1):16. doi: 10.1007/s13317-016-0088-8

The CPT Codes provided in this document are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payor being billed. Any Profile/panel component may be ordered separately. Reflex tests are performed at an additional charge.