Tests for Rheumatoid Arthritis Chua, Kathleen

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

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

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

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

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

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

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

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

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

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.

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.