antinuclear factor

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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)

Notes:

  • 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)

Reference:

  • 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.

Last reviewed 01/2018

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