Pathology Handbook

ENA

Synonyms

Extractable nuclear antigens

Clinical Indications

  • Sjogren's syndrome
  • SLE
  • Cutaneous lupus
  • Neonatal lupus 
  • Congenital complete heart block
  • Mixed Connective Tissue Disease
  • Systemic Sclerosis
  • Polymyositis
  • Dermatomyositis

Test Includes

Detection of IgG autoantibodies against saline extracted cellular antigens.
Samples are initially screened by an EIA which includes the following antigens: RNP; Sm; SSa (Ro); SSb (La); Scl-70; Jo-1 and centromere B. If found to be positive, samples are subsequently tested for the individual specificities

Request Form 

Request via ICE

Availability

Screening test is performed daily (Monday-Friday). Profile is performed weekly.

Specific Criteria

It is essential to provide relevant clinical information.
Only samples found to be ANA positive will be referred for ENA testing unless clinical information suggests testing may be relevant

Turnaround Time

All samples are generally sent to referral laboratory within 3 working days of receipt in the laboratory. Screening test is performed daily (Monday-Friday). Profile is performed weekly.

Specimen

Serum

Volume

7 ml

Container

Vacutainer red top

Collection

Samples should be transported to the laboratory immediately

Lab Handling

Aliquot and store at 4-8°C prior to testing and at -20°C or below for up to 1 month after receipt.

Causes for Rejection

Unlabelled/inadequately labelled sample.
Inadequately completed request form.
Delay in sample reaching laboratory

Reference Range

Reference range (Ratio):

Negative :  less than 0.7 
Equivocal:  0.7 - 1.0 
Low Positive: 1.0 - 4.0
Moderate Positive: 4.0 - 10.0 
Strong Positive: >10.0

Below are listed the specificities routinely tested for and their clinical associations:

Anti Ro (SSa): Associated with Sjogren's syndrome, SLE, cutaneous lupus and congenital complete heart block.

Anti La (SSb): Associated with Sjogren's syndrome, SLE and neonatal lupus.

Anti Sm: Specific for SLE. Found in approximately 25 - 40% of patients, but reported to be seen most frequently in West Indians with SLE. Rarely found in Caucasians.

Anti RNP: Associated with SLE and, when occurring alone, to identify MCTD.

Anti Scl-70: Found in 20 - 40% of patients with progressive systemic sclerosis and 20% of patients with limited sclerosis.

Anti Jo-1: Associated with polymyositis, pulmonary fibrosis and Dermatomyositis.

Anti Centromere B: Found in 70 -80% of patients with CREST