When to request ANA testing (Connective Tissue Disease)
These are a group of systemic autoimmune conditions, that are associated with a range of clinical symptoms. In the general population, SLE is estimated to have a UK prevalence of 12-28 per 100,000 (1), with higher rates seen in association with Afro-carribbean populations. The diagnosis of many autoimmune conditions including SLE relies on indentifying the presence of clinical features (for example, as defined by the American College of Rheumatology ACR criteria for SLE).
Autoantibody testing for these conditions (including ANA testing, dsDNA and ENA antibody testing) are not suitable screening tests for these conditions, as positive ANA has been reported to be seen in up to 20-30% of healthy individuals (reviewed in 2). Furthermore, many patients may have systemic autoimmune disease that requires specialist referral, regardless of autoantibody testing results.
ANA testing is indicated in the following (3):
- Suspected Sjogren’s Syndrome (dry eyes, dry mouth)
- Suspected Scleroderma (skin thickening, oesophagitis, severe Raynaud’s, digital ulceration)
- Patients with two or more of the following:
- Photosensitive rash, malar rash or discoid rash
- Evidence of inflammatory arthritis
- Recurrent oral ulceration (excluding aphthous ulcers)
- Unexplained pleurisy or pericarditis
- Unexplained proteinuria or haematuria
- Recurrent miscarriage
- Unexplained neurological symptoms (seizures, psychosis, early onset stroke)
- Haemolytic anaemia, thrombocytopenia or leukopenia
- Scarring alopecia
The laboratory will reflexly test for ENA antibodies in all ANA positive tests with a speckled pattern (level of 1:160 or above).
The laboratory will reflexly test for dsDNA antibodies for all ANA positives with a homogeneous pattern (level of 1:80 or above).
ANA testing will not be performed if relevant clinical details are not provided. The senior BMS staff / Clinical Immunologist can be contacted to discuss any matters further by telephone if required.
Further information is available on RefHelp (Rheumatology section: Connective Tissue Disease)
References:
https://www.lupusuk.org.uk/medical/gp-guide/introduction-to-lupus/epidemiology-of-lupus/ (Accessed 6.3.18)
Pisetsky DS. Anti-nuclear antibody testing – misunderstood or misbegotten? Nature Reviews Rheumatology 13, 495-502 (2017)
