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PTD-222

Test Directory - DNA Antibody

Synonyms

Double stranded, or native, DNA antibody, (dsDNA), (nDNA),

Clinical Indications

Investigation and monitoring of connective tissue diseases. dsDNA antibodies are strongly associated with SLE.

Part of Profile

Automatically done on positive ANA samples

Request Form

Combined Pathology Blood form (Yellow/Black)

 

Availability

Referral test: Analysed by Immunology, Southend Hospital.

Specific Criteria

Positive ANA, monitoring known SLE patients.

Patient Preparation

 

None required

Turnaround Time

7 working days

Specimen

Serum

Volume

2 ml

Container

Yellow top (SST) tube or

Paediatric orange top (lithium-heparin)

Lab. Handling

Aliquot and store at 4C

Causes for Rejection

Assay within previous month

Interpretation

 

Negative: Active SLE is unlikely when the Crithidia result is negative.
Positive: Consistent with active SLE

We have recently reviewed our method for testing dsDNA antibodies. The current 'Unicap' method gives a quantitative result however, with this method, many positive results do not correlate with the presence of SLE, or with our 'reference' Crithidia method, which we use to confirm all new positive results. A recent audit suggests that the Unicap method is more prone to these false positives than previously realised. In view of the potential for diagnostic error and unnecessary referral, we will now be doing Crithidia testing as the first line assay. We will continue to use the quantitative Unicap method for monitoring of known SLE patients.

Lab. Handling

Processing: Aliquot (MPA) and store at 4C in separating fridge (CB39), southend immunology rack.
Referral
:  DNA and send or IMDUP and track at 4C in cold room (CB23).


Version 1.0 / July 2014                                                                                                            Approved by: Consultant Biochemist