- This test is done on the serum of the patient.
- How to get good serum: Take 3 to 5 ml of blood in the disposable syringe or in vacutainer. Keep the syringe for 15 to 30 minutes at 37 °C and then centrifuge for 2 to 4 minutes to get clear serum.
- No fasting or preparation is required.
Purpose of the test
- For the diagnosis of Systemic lupus erythematosus (SLE ).
- Positive in other autoimmune diseases.
- Drugs may cause false positive tests like aminosalicylic acid, chlorothiazide, procainamide, acetazolamide, penicillin, phenytoin sodium, and griseofulvin.
- Drugs may cause false negative test like steroids.
- This test may be positive after the viral infection and some of the chronic infection.
- The antinuclear antibodies are produced in connective tissue diseases (autoimmune diseases ) against various antigens in the nucleus like RNA, DNA, histones, and ribonucleoprotein.
- Autoantibodies are directed against nuclear material (ANA) or against cytoplasmic material called anti-cytoplasmic antibodies.
- The major antinuclear antigens are:
- DNA (double and single-stranded).
- Nuclear proteins.
- 95% of SLE patients shows ANA.
- This ANA is not specific for SLE, so it has to be supplemented by other tests.
- Fluorescent staining under an ultraviolet microscope shows different patterns and increase the specificity of this test.
- Fluorescent patterns show different staining in the nucleus e.g.:
- The homogeneous pattern is seen in SLE and mixed connective tissue disease.
- Peripheral outline only is seen in SLE.
- The speckled pattern has seen other autoimmune diseases like SLE, Sjogren’s syndrome, Scleroderma, Rheumatoid arthritis., and mixed connective tissue disease.
- The nuclear pattern is seen in Scleroderma and Polymyositis.
- ANA is gamma globulin and belongs to more than one type of immunoglobulin.
- There are ANA-negative cases of SLE.
- Some believe that negative ANA excludes the SLE.
- Diseases with positive antinuclear antibodies.
||Positivity of ANA %
||another source positivity %
||90 to 100
|Mixed connective tissue disease
- These are negative.
- When done with a dilution of the serum then titer of more than 1:32 is positive.
- Negative at 1:20 dilution.
- It helps in the diagnosis of Autoimmune diseases and particularly Systemic lupus erythematosus (98%) but with poor specificity.
- This test is positive 30 to 50% in other autoimmune diseases such as Rheumatoid arthritis, Sjogren’s syndrome ( 70 %) and Polymyositis and other related diseases.
If ANA negative then SLE can be excluded.
The positive or increased level of ANF:
- Rheumatoid arthritis.
- Polyarteritis Nodosa
- Sjogren’s syndrome.
- Other autoimmune diseases.
- Chronic hepatitis.
The nucleus is pushed by the antinuclear antibody.
Possible References Used
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