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Antinuclear Antibodies (ANA)

30 Azn
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Antinuclear antibodies (ANA) are autoantibodies that target nuclear antigens and are widely used in the diagnosis of autoimmune diseases. There are more than 100 types of ANA, and they are detected in 90% of patients with systemic connective tissue diseases such as:

  • Systemic lupus erythematosus (SLE)
  • Systemic scleroderma
  • Sjögren’s syndrome
  • Mixed connective tissue disease (MCTD)

Mechanism of Action

ANA formation is linked to apoptosis of keratinocytes and lymphocytes, which sensitizes the immune system to nuclear antigens. The immune complexes (antigen-antibody) deposit on basement membranes and blood vessels in various organs (skin, kidneys, synovial and serous membranes, brain, etc.), leading to inflammation and tissue damage.

In some cases, ANA elevation is observed in infections and cancer, but in these conditions, antibody levels tend to be unstable and decrease quickly.

  • Sample: Blood serum (venous blood).
  • Fasting is not required, but the test should be taken at least 4 hours after a light meal.

ANA testing is performed to:

  • Diagnose systemic connective tissue diseases.
  • Assess the progression of rheumatic diseases.
  • Differentiate autoimmune disorders.
  • Investigate symptoms of autoimmune diseases, such as:
    • Prolonged fever
    • Unexplained weight loss
    • Myalgia (muscle pain)
    • Photosensitivity
    • Raynaud’s syndrome (fingers turning white, then blue, then red in response to cold or stress)
    • Leukopenia (low white blood cell count)
    • Hemolytic anemia

Interpretation of ANA Test Results

Elevated ANA Levels May Indicate:

  • Systemic connective tissue diseases (e.g., lupus, scleroderma, Sjögren’s syndrome, MCTD)
  • Infections:
    • Tuberculosis
    • Chronic active hepatitis
    • HIV infection
    • Bacterial endocarditis
  • Diabetes mellitus
  • Pulmonary fibrosis
  • Multiple sclerosis

Important Considerations

  • Repeat testing may be required after a certain period to confirm ANA elevation due to an autoimmune process.
  • ANA titers may vary between laboratories depending on the testing methods and antigen panels used.

This test is essential for early diagnosis, monitoring, and differentiation of autoimmune diseases.