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EPIC CODE: SCL70 Scl 70 Antibodies, IgG, Serum

Reporting Name

Scl 70 Ab, IgG, S

Useful For

Evaluating patients with signs and symptoms of scleroderma and other connective tissue diseases in whom the test for antinuclear antibodies is positive

 

Testing for Scl 70 antibodies are not useful in patients without demonstrable antinuclear antibodies.

Testing Algorithm

For more information see Connective Tissue Disease Cascade.

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Specimen Type

Serum


Specimen Required


Container/Tube:

Preferred: Serum gel

Acceptable: Red top

Specimen Volume: 0.5 mL


Specimen Minimum Volume

0.4 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Serum Refrigerated (preferred) 21 days
  Frozen  21 days

Special Instructions

Reference Values

<1.0 U (negative)

≥1.0 U (positive)

Reference values apply to all ages.

Day(s) Performed

Monday through Saturday

Test Classification

This test has been cleared, approved, or is exempt by the US Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.

CPT Code Information

86235

LOINC Code Information

Test ID Test Order Name Order LOINC Value
SCL70 Scl 70 Ab, IgG, S 47322-3

 

Result ID Test Result Name Result LOINC Value
SCL70 Scl 70 Ab, IgG, S 47322-3

Clinical Information

Scl 70 (topoisomerase 1) is a 100-kD nuclear and nucleolar enzyme. Scl 70 antibodies are considered to be specific for scleroderma (systemic sclerosis) and are found in up to 60% of patients with this connective tissue disease. Scl 70 antibodies are more common in patients with extensive cutaneous involvement and interstitial pulmonary fibrosis, and are considered a poor prognostic sign.(1,2)

 

For more information see Connective Tissue Disease Cascade.

Interpretation

A positive test result for Scl 70 antibodies is consistent with a diagnosis of scleroderma.

Cautions

No significant cautionary statements

Clinical Reference

1. Homburger H, Larsen S: Detection of specific antibodies. In Clinical Immunology: Principles and Practice. First edition. Edited by R Rich, T Fleisher, B Schwartz, et al. St. Louis, Mosby-Year Book, Inc, 1996, pp 2096-2109

2. White B: Systemic sclerosis. In Clinical Immunology Principles and Practice. Second edition. Edited by R Rich, T Fleisher, W Shearer, et al. St. Louis, Mosby-Year Book, 2001, pp 64.1-64.10

Method Description

Recombinant Scl 70 antigen is bound to polystyrene microspheres, which are impregnated with fluorescent dyes to create a unique fluorescent signature. Scl 70 antibodies, if present in diluted serum, bind to the Scl 70 antigen on the microspheres. The microspheres are washed to remove extraneous serum proteins. Phycoerythrin (PE)-conjugated antihuman IgG antibody is then added to detect IgG anti-Scl 70 bound to the microspheres. The microspheres are washed to remove unbound conjugate, and bound conjugate is detected by laser photometry. A primary laser reveals the fluorescent signature of each microsphere to distinguish it from microspheres that are labeled with other antigens, and a secondary laser reveals the level of PE fluorescence associated with each microsphere. Results are calculated by comparing median fluorescence response for Scl 70 microspheres to a 4-point calibration curve.(Package insert: Bioplex 2200 ANA Screen. Bio-Rad Laboratories, Hercules, CA 11/2011)

Report Available

1 to 3 days

Specimen Retention Time

14 days

Reject Due To

Gross hemolysis Reject
Gross lipemia Reject
Gross icterus OK

NY State Approved

Yes

Method Name

Multiplex Flow Immunoassay

Secondary ID

80178