A raised antinuclear factor (ANF) is almost always present in SLE (80-90% - note that uraemia may render the result negative) (1).
Other conditions that are associated with a positive ANF but usually of lower titre than in SLE, include:
- systemic sclerosis (80%)
- Sjogren's syndrome (60%)
- polymyositis/dermatomyositis (30%)
- Still's disease (30%)
Also seen in:
- autoimmune chronic active hepatitis
- primary biliary cirrhosis
- infections, infective endocarditis
- fibrosing alveolitis
- drug reactions
Occasionally a positive ANF is found in normal elderly people.
Some patients are ANA positive but have antibodies which recognise different sets of nuclear proteins, termed extractable nuclear antigens (ENA)
- the commonest is anti-Ro which is usually clinically associated with photosensitivity (1)
- low-titre ANF (titres of <=1:80) may be clinically insignificant. Higher titres may be seen in various conditions, including RA and connective tissue diseases, and sometimes in viral and chronic infections (2)
- 1) ARC. Connective tissue disease in primary care. Hands On 2006; 9:1-5.
- 2) ARC.The approach to the patient presenting with multiple joint pain. Hands On 2012; 7(1):1-12.