1. Tests for Rheumatoid Arthritis
Chua, Kathleen

2. Laboratory Findings Rheumatoid factors
Antibodies to Cyclic Citrullinated Peptide (Anti-CCP)
CBC with differential count
Erythrocyte sedimentation rate
Synovial Fluid Analysis

3. What are Rheumatoid Factors?
Autoantibodies reactive with the Fc portion of IgG
Its presence is NOT specific for RA
Frequency increases with age
10-20% of individuals >65 y/o test positive despite not having RA

4. Other conditions associated with the presence of rheumatoid factors:
Systemic Lupus Erythematosus
Sjögren’s Syndrome
Chronic liver disease
Sarcoidosis
Interstitial pulmonary fibrosis
Infectious mononucleosis
Hepatitis B
Tuberculosis
Leprosy
Syphillis
Subacute bacterial endocarditis
Visceral leishmaniasis
Schistosomiasis
Malaria
Healthy individuals
> 65 years old
Post-vaccination
Post-transfusion
Relatives of patients with RA

5. Rheumatoid factor is used only to evaluate
Rheumatoid factor is used only to evaluate. It is NOT used as a screening procedure
Predictive value of the presence of rheumatoid factor in determining a diagnosis of RA is poor
< 1/3 of patients with (+) rheumatoid factor will be found to have RA
Evaluate severity and progression
↑ titer = ↑ severity

6. Anti-Cyclic Citrullinated Peptide (Anti-CCP)
Most commonly found in patients with:
(+) rheumatoid factor
Aggressive disease  bone errosions
RA-associated HLA-ß1 allele
Smokers
Early detection of RA
Sensitivity: anti-CCP = rheumatoid factor
Specificity: anti-CCP > rheumatoid factor
Confirm diagnosis, establish prognosis
Disadvantage vs. rheumatoid factor: not useful in predicting the future development of RA
Can’t evaluate severity and progression

7. Hematologic Findings
Complete Blood Count w/ Platelet Count and Differentials
Normochromic, normocytic anemia
ineffective erythropoiesis
Thrombocytosis
Usually normal WBC count but…
May have mild leukocytosis
Felty’s syndrome – leukopenia
Severe systemic disease – eosinophilia
↑iron stores in bone marrow
↑ erythrocyte sedimentation rate

8. Other serologic findings
Acute phase reactants
Ceruloplasmin
C-reactive protein
Correlate with disease activity and likelihood of progressive joint damage

9. Synovial fluid analysis
Confirms presence of inflammatory arthritis
Non-specific
Characteristics of synovial fluid
Physical
Turbid
Reduced viscosity
Clinical chemistry
Increased protein content
Normal / slightly decreased glucose concentration
Cell count
WBC varies from 5 to 50,000/uL; PMNs predominate
>2000/uL with > 75% PMNs = inflammatory arthritis
Non-diagnostic of RA
C3 & C4 markedly diminished

10. Radiographic Evaluation
None of the radiographic findings is diagnostic of RA
Early in the disease – usually NOT helpful; will only reveal the “obvious”, not help significantly in management
As the disease progress – abnormal findings more pronounced

11. Characteristic patterns of abnormalities seen in radiographs
Symmetric involvement
Juxtaarticular osteopenia
Loss of articular cartilage
Radiography would determine the extent of cartilage destruction
Bone erosion
X-rays of the hands in Rheumatoid arthritis. Demonstrates periarticular porosis, joint space narrowing of the proximal interphalyngeal joints, and erosions. Note erosion of the ulnar styloid, and narrowing of the wrists. (See Fig 12)
X-rays of the hands in Rheumatoid arthritis. Demonstrates periarticular porosis, joint space narrowing of the proximal interphalyngeal joints, and erosions. Note erosion of the ulnar styloid, and narrowing of the wrists.

12. Other imaging procedures
99mTc bisphosphonate bone scanning
MRI
Technetium-99 bone scan in a patient complaining of stiffness and painful joints but a NORMAL examination, showing uptake of technetium in sub clinical inflammation of joints. Note symmetrical, polyarticular uptake pattern (hands, feet and knees demonstrated)- typical of Rheumatoid arthritis.
Technetium-99 bone scan in a patient complaining of stiffness and painful joints but a NORMAL examination, showing uptake of technetium in sub clinical inflammation of joints. Note symmetrical, polyarticular uptake pattern (hands, feet and knees demonstrated)- typical of Rheumatoid arthritis.