Anti-Nuclear Antibody (ANA) Connective Tissue Disease (CTD) Screen & ANA Hep2 immunofluorescence (IIF)
| Category | Immunology |
|---|---|
| Test background |
The presence of ANA is a gateway criteria for the diagnosis of SLE (EULAR/ACR 2019). ANA are also found in a number of other autoimmune diseases, such as Sjögren’s syndrome (60%), rheumatoid arthritis, autoimmune liver disease, scleroderma, mixed connective tissue disease, poly/dermatomyositis, Hashimoto’s thyroiditis and autoimmune haemolytic anaemia. A positive ANA is a risk factor for uveitis in patients with juvenile idiopathic arthritis (JIA). Weak positive (titres up to 1/320) ANA reactions are not uncommon, especially in the elderly, and may have no clinical significance. ANA may be present during acute and chronic infection. The laboratory performs a connective tissue disease (CTD) screen (ANA screen) first line for the most common ANA. Any positive results will be further tested by ANA immunofluorescence (Hep2 IIF, ANA IIF) and confirmatory ENA profile plus quantitative double stranded DNA antibodies. ANA IIF is reported in accordance with the International Consensus on ANA Patterns (ICAP) recommendations and more details of pattern associations can be found on their website https://anapatterns.org/index.php. The CTD screen is a bead based fluoroenzymeimmunoassay containing the following recombinant antigens; dsDNA, Ro52, Ro60, SSB/La, Sm, U1RNP (RNP-70, A, C), Jo-1, Scl-70, CENP-B, Mi-2, RNA Pol III, PM-Scl, PCNA, Ribosomal P, and Fibrillarin. |
| Clinical Indications |
Suspected connective tissue disease. |
| Reference range | ANA Immunofluorescence = Negative titre <1/160 (range verified in house) |
| Sample & container required | Serum (rust top RST tube) |
| Sample volume | 5-10 mL blood (1 mL serum) |
| Turnaround time | 4 days |
| Notes | ANA by IIF is awaiting accreditation due to a change in platform. |