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Anti-dsDNA (Double-stranded) Ab by Farr method (RDL)

CPT: 86225

Synonyms

  • Double Stranded DNA by Farr
  • dsDNA
  • DsDNA Farr
  • Farr
  • Lupus
  • SLE

Expected Turnaround Time

5 days


Specimen Requirements


Specimen

Serum


Volume

1 mL


Minimum Volume

0.3 mL (Note: This volume does not allow for repeat testing.)


Container

Red-top tube or gel-barrier tube


Collection

Separate serum from cells within one hour of collection. Transfer to a plastic transport tube before shipping. To avoid delays in turnaround time when requesting multiple tests on frozen samples, please submit separate frozen specimens for each test requested.


Storage Instructions

Refrigerate or freeze.


Stability Requirements

Temperature

Period

Room temperature

7 days

Refrigerated

14 days

Frozen

60 days

Freeze/thaw cycles

Stable x1


Causes for Rejection

Grossly hemolyzed; bacterial contamination; lipemic specimen; icteric specimen; non-serum specimen types


Test Details


Use

The Farr method detects the high-affinity anti-dsDNA antibodies. The Farr assay is the most specific method for detecting dsDNA auto antibodies. Significant elevations in dsDNA autoantibody concentrations confirm the diagnosis of systemic lupus erythematosus (SLE). Serial studies of elevated values of dsDNA auto antibodies are useful for predicting activity of SLE and for measurement of serum C3 or C4 concentrations. Absence of dsDNA autoantibodies does not exclude the diagnosis of SLE. Doubling of dsDNA autoantibody concentrations or increases greater than 30 IU/mL in less than 10 weeks are reliably predictive of exacerbations of SLE. A simultaneous decrease in serum C4 complement enhances this predictive value.


Limitations

This test was developed and its performance characteristics determined by LabCorp. It has not been cleared or approved by the Food and Drug Administration.


Methodology

Radioimmunoassay (RIA) Farr Technique


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