Anti-nuclear antibodies (ANA)
Investigation : Anti-nuclear antibodies (ANA)
Spec container : Serum Gel 
Volume required : 5ml
Reference range : Negative
Turnaround : 7 days
Methodology: Indirect immunofluorescence microscopy. Hep2 substrate. IgG-specific antibody.

Indications: Antinuclear antibodies are present in many rheumatic diseases, and often are not specific for any single disease. They are frequently associated with Systemic Lupus Erythematosus (SLE) and scleroderma (SCL), and in lower frequencies in rheumatoid arthritis (RA), Sjogren's syndrome (SS), mixed connective tissue disease (MCTD) and polymyositis/dematomyositis (PM/DM). There can be considerable overlap in the types of nuclear antibodies detected; the more common patterns are listed below:

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- Homogeneous staining suggests anti-DNA or anti-histone antibodies observed in SLE, RA and drug-induced SLE.

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- A variety of speckled patterns are assocoiated with a number of conditions including SLE, Sjogrens, MCTD, RA and scleroderma

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- Nucleolar staining is observed in scleroderma and some form of Raynaud's phenomenon.

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- A centromere pattern is observed in the CREST syndrome of limited scleroderma; CREST = calcinosis, Raynaud's phenomenon, oesophogeal hypomotility, sclerodactly and telangiectasia

Related tests:
In the event of the ANA being positive the following tests will also be performed:
  • ANA Hep2 Titre
    A titre of 1:160 or above is considered a significant positive.
  • Anti-double stranded DNA (dsDNA)
    Antibodies to native dsDNA occur in high titre in approximately 70 percent of patients with SLE, but are also observed occasionally in patients with RA, drug-induced SLE or Sjgren's syndrome. First line screening is performed by ELISA with positive tests confirmed by Farr radioimmunoasssay.
  • Extractable nuclear antigen antibodies (ENA)
    First line screening is performed by ELISA comprising a mixture of six ENAs. A positive result is further tested by immunoblot assay to determine specificity for Sm, RNP, SSA(Ro), SSB(La), Jo-1 or Scl-70

ENA's and Connective Tissue Diseases
Disease (% prevalence)
U1-RNP MCTD (100%)
SLE (30% - 40%)
Sm SLE (20% - 30%); highly specific
Ro/SS-A Sjogren's syndrome (60% - 75%)
SLE (40% - 50%)
Subacute cutaneous LE (100%)
Neonatal LE - maternal (100%)
La/SS-B Sjogren's syndrome (10% - 40%)
SLE (6% - 15%)
Subacute cutaneous LE (25% - 35%)
Neonatal LE - maternal (90%)
Scl-70 Scleroderma - diffuse form (25%)
Jo-1 Polymyositis/ /dermatomyositis (25% - 68%)
Reference: Autoantibodies; J.B. Peter & Y. Schoenfield


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