Laboratory Tests in Rheumatology Aims of lab test: 1. Identification of pathological process in the...
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Transcript of Laboratory Tests in Rheumatology Aims of lab test: 1. Identification of pathological process in the...
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.
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.
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
Laboratory Tests in Rheumatology
Laboratory Tests in Rheumatology
• 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
Laboratory Tests in Rheumatology
Laboratory Tests in Rheumatology
Laboratory Tests in Rheumatology
• 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
Laboratory Tests in Rheumatology
• Conditions associated with ANA– Systemic lupus erythematosus 95%– Systemic sclerosis 90%– Sjogren syndrome 80%– Rheumatoid arthritis 60%– Polymyositis 40%– Chronic active hepatitis 100%– Drug induced lupus 100%– Diabetes 25%– Normal 8%
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%).
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%).
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.
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 Wegener’s 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.
Laboratory Tests in Rheumatology
Laboratory Tests in Rheumatology
•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.
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.
Laboratory Tests in Rheumatology
• Color
• Normal- yellow.
• Hemarthrosis- orange, red.
• Inflammatory arthropathy- white, cream.
• Clarity
• Normal- transparent.
• More particles and/or cells- opaque.
Laboratory Tests in Rheumatology
• Viscosity
• Normal- high.
• Inflammatory- enzymatic degradation viscosity .
Laboratory Tests in Rheumatology
Laboratory Tests in Rheumatology
•No. Cells (cells/mm)
•Normal < 200
•Non-inflammatory arthropathy < 2000•Inflammatory arthropathy> 200050,000
•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.
Laboratory Tests in Rheumatology
•Crystals
• Mono-sodium-urate Monohydrate Gout.
• Ca-pyrophosphate Dihydrate Chondrocalcinosis, Pseudogout.
• Culture
Laboratory Tests in Rheumatology