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Rheumatoid Factor

Rheumatoid factor is an autoantibody directed against IgG that contributes to the disease process in rheumatoid arthritis. A positive RF test supports a diagnosis of RA, though 15% of RA patients test negative. Higher RF levels correlate with worse joint destruction and systemic involvement. RF testing is commonly used to help diagnose RA along with clinical symptoms and imaging, though additional serological tests exist.

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50 views11 pages

Rheumatoid Factor

Rheumatoid factor is an autoantibody directed against IgG that contributes to the disease process in rheumatoid arthritis. A positive RF test supports a diagnosis of RA, though 15% of RA patients test negative. Higher RF levels correlate with worse joint destruction and systemic involvement. RF testing is commonly used to help diagnose RA along with clinical symptoms and imaging, though additional serological tests exist.

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Sasa Abass
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RHEUMATOID ARTHRITIS

(Microbiology)
Group Members :
Samjhana Sharma (73)
Sashi Kumar Yadav (74)
Sat Prasad Nepal (75)
Sharmila Phellu (76)
Shraddha Shrestha (77)
Shuvechha Pandey (78)
Srijana Shakya (79)
Sulabh Shrestha (80)
Surakshya Rayamajhi (81)
Surendra Pariyar (82)
Sushil Dulal (83)
Sushmita Bajagain (84)
Tulsi Ram Shrestha (85)
Uday Chandra Prakash (86)
Objectives:

• To define Rheumatoid Factor.

• To explain briefly its significance


in the diagnosis of rheumatoid
arthritis.
Rheumatoid factor
 Rheumatoid factor (RF) is an autoantibody that is
directed against organism’s own tissues, most
relevant in rheumatoid arthritis.

 An antibody against the Fc portion of IgG, which is


itself an antibody. RF and IgG join to form

immune
complexes which contribute to the disease process.
Diagnosis of RA
• Diagnosis is based on clinical test, signs and symptoms and
imaging technique.

• The test for RF may be ordered when a person has signs of


RA.

• Symptoms : pain, warmth, swelling, and morning stiffness in


the joints, nodules under the skin

• X-rays of swollen joint capsules

• An RF test may be repeated when the first test is


negative and symptoms persist.
Rheumatoid Factor
• Significant associations : rheumatoid disease
including Rheumatoid Arthritis.

• Higher the level of RF, the worse the joint


destruction and greater the chance of
systemic involvement.
Associations
• Rheumatoid arthritis  60-70%
• Sjögrens syndrome  ≤100 %
• Felty's syndrome  ≤100 %
• Systemic sclerosis  30%
• Infective endocarditis  ≤ 50%
• Systemic lupus erythematous  ≤ 40%
• Infectious mononucleosis
• Hepatitis
• TB
• Cancer
RF Test
RF is commonly used as a blood test for the
diagnosis of rheumatoid arthritis.

A negative RF is seronegative, in about 15% of


patients.

During the first year of RA, RF is more likely to


be negative but some individuals convert to
seropositive later.
CRITERIA
• High levels of rheumatoid factor

• Generally above 20 IU/mL

• Upto dilution level 1:40 (of rheumatoid


factor)

• In 80% cases
Other Serological Tests
• New test for the presence of anti-citrullinated
protein antibodies (ACPAs).
• Autoimmune-related tests:
- ANA (antinuclear antibody)
- CRP (C-reactive protein)
- ESR (erythrocyte sedimentation rate)
- CBC (Complete Blood Count)
SUMMARY
• Rheumatoid factor (RF) an antibody (IgM)

• It is used for the diagnosis of Rheumatoid


arthritis

• But it is not the confirmational test because it


is observed in other related and unrelated
diseases
“Thank You”
• Sources:
• Wikipedia.com
• About.com
• WebMd.com
• Textbook of Microbiology
(Anantanarayan and
Panicker)

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