Specimen Type: Serum
Container: 1 Serum Separator Tube (SST)
Preferred Vol: 1.00 mL
Min Vol: 0.50 mL
Farr Radiobinding Assay (FARR RBA)
Monday - Saturday
The Farr method is the most sensitive method for detecting dsDNA autoantibodies. Significant elevations in dsDNA autoantibody concentrations confirm the diagnosis of systemic lupus erythematosus (SLE). Serial studies of elevated values of dsDNA autoantibodies 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 30.0 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.