Laboratory Tests in Rheumatology Aims of lab test: 1. Identification of pathological process in the body & evaluation of its severity. 2. Support or negation

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  • Laboratory Tests in Rheumatology Aims of lab test: 1. Identification of pathological process in the body & evaluation of its severity. 2. Support or negation of specific diagnosis. 3. Follow up of disease & complications. 4. Detection of adverse reactions of drug therapy. * Interpretation of lab tests should be done only in relation of certain clinical context. Without the clinical picture most lab tests are useless.
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  • Laboratory Tests in Rheumatology Erythrocyte Sedimentation Rate ESR The most practical indicator to acute phase response. Not every inflammation is accompanied by elevated ESR, especially if mild or chronic. Reflects mainly fibrinogen and immunoglobulins. Roles: 1. Indicator to organic disease (nonspecific). 2. Monitoring disease activity. 3. Monitoring response to therapy. Values: men- age/2; women- (age+10)/2.
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  • Laboratory Tests in Rheumatology C-reactive protein Biological ligands: phosphocholine, phospholipids, histone Activation of classic complement pathway Interaction with immunocytes by binding to Fc gamma receptor Sensitive marker of inflammation
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  • Laboratory Tests in Rheumatology
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  • Immunological Tests a. Protein electrophoresis.. Identification of monoclonal Ab: MM, lymphoproliferative, cryoglobulins, rheumatic disease.. Elevated -globulins. b. Complement.. Immune complexes disease: SLE, SBE, severe RA.. Monitoring lupus nephritis. C deficiency. c. Autoantibodies. Intracellular: nuclear components (ANA), cytoplasmic.. Membranals.. Extracellular
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  • Laboratory Tests in Rheumatology
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  • Anti-cyclic citrullinated peptide antibodies Directed against citrulline residues formed in post translational modifications of arginine Highly specific (98%) Moderately sensitive (68%) Marker of prognosis or of disease severity
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  • Laboratory Tests in Rheumatology Conditions associated with ANA Systemic lupus erythematosus95% Systemic sclerosis90% Sjogren syndrome80% Rheumatoid arthritis60% Polymyositis40% Chronic active hepatitis100% Drug induced lupus100% Diabetes25% Normal8%
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  • Laboratory Tests in Rheumatology Anti-DNA SLE.. Marker for disease activity.. In correlation with kidney damage. Anti- Histone 95% 0f patients with drug lupus (procainamide, quinidine, hydralazine, phenitoin) fever, arthritis, respiratory symptoms. Anti- Sm Specific for SLE. Sensitivity (30%).
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  • Laboratory Tests in Rheumatology Anti- RNP Specific to U1 RNA. Specific to MCTD (100%). Anti- Centromere 80-90% of cases with limited scleroderma. Anti- Scl-70 Scl-70 = DNA topoisomerase I, an intracellular enzyme involved in the initial uncoiling of DNA. Specific to diffuse scleroderma. Sensitivity (10-20%).
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  • Laboratory Tests in Rheumatology Anti-ssA SsA shows homology to calreticulin- Ca binding intracellular protein. . SLE. . Neonatal lupus. . Sjogren syn. especially + extra-articular manifestations. . Subacute cutaneous lupus. Anti-ssB ssB =RNA binding protein. . Sjogren syn. . SLE.
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  • Laboratory Tests in Rheumatology Anti-neutrophil cytoplasmic Abs Abs against cytoplasmic Ags in PMN>> Monocytes. 2 principal forms: 1.C-ANCA. Cytoplasmic granular staining. Anti-proteinase 3. Specific to Wegeners granulomatosis. In active disease up to 90%. In remission 30%. Possible marker for disease activity. 2. P-ANCA. Perinuclear staining. Anti-myeloperoxidase. Non specific marker of necrotizing vasculitis: . Churg-Strauss. . MPA. . GN.
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  • Laboratory Tests in Rheumatology
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  • HLA B-27: 90% of AS patients. 8% normal population. DR-4: 67% of white population with RA. 30 % of normals. * Useless as routine test. * Take B-27 when high clinical suspicion for AS + normal X film.
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  • Laboratory Tests in Rheumatology Synovial Fluid Transudate of plasma enriched with high m.w. saccharides, mostly hyaluronans. Indication for arthrocentesis:.Monoarthritis (acute or chronic)..Infection..Crystal induced arthropathy..Trauma + effusion.
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  • Laboratory Tests in Rheumatology Color Normal- yellow. Hemarthrosis- orange, red. Inflammatory arthropathy- white, cream. Clarity Normal- transparent. More particles and/or cells- opaque.
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  • Laboratory Tests in Rheumatology Viscosity Normal- high. Inflammatory- enzymatic degradation viscosity .
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  • Laboratory Tests in Rheumatology
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  • No. Cells (cells/mm) Normal < 200 Non-inflammatory arthropathy < 2000 Inflammatory arthropathy> 2000 50,000 Arthropathy with cells> 25,000: .Septic arthritis. .Crystal induced arthropathy. .Reactive arhtritis. .RA. Inflammatory arthropathy/ Intra-articular hemorrhage 60- 80% PMN. Non-inflammatory arthropathy Mononuclears, synoviocytes.
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  • Laboratory Tests in Rheumatology Crystals Mono-sodium-urate Monohydrate Gout. Ca-pyrophosphate Dihydrate Chondrocalcinosis, Pseudogout. Culture
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  • Laboratory Tests in Rheumatology