Rheumatology Question 2 Instructor

What proportion of the general population is ANA-positive at a titer of 1:40? 1:160?

ANA titers of 1:40 are thought to be present in about 30% of the healthy population. The likelihood of a connective tissue disease rises with the ANA titer.

An ANA of 1:80 is seen in 13% of individuals, while an ANA of 1:160 is found in 5%. An ANA of 1:320 is seen in only 3.3% of healthy people.

Name four rheumatologic diagnoses that are associated with a positive ANA and four non-rheumatologic conditions that are associated with a positive ANA.

Estimates of the prevalence of ANA positivity in rheumatologic diseases:

  1. SLE: 98%
  2. Scleroderma: 85%
  3. Sjogren’s: 48%
  4. Rheumatoid arthritis: 41%
  5. Dermatomyositis and polymyositis: 61%
  6. Mixed connective tissue disease: 93%
  7. Drug-induced lupus: 100%
  8. Discoid lupus: 15%
  9. Pauciarticular juvenile idiopathic arthritis: 71%

Non-rheumatologic diseases associated with ANA-positivity:

  1. Grave’s disease or Hashimoto’s thyroiditis
  2. Hepatitis C
  3. Pimary biliary cirrhosis
  4. Autoimmune hepatitis
  5. Idiopathic pulmonary hypertension
  6. Subacute bacterial endocarditis
  7. Tuberculosis
  8. HIV
  9. Leukemia
  10. Lymphoma

Tan EM, Feltkamp TE, Smolen JS et al. Range of antinuclear antibodies in “healthy” individuals. Arthritis Rheum 1997 Sep; 40(9): 1601-11

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