Makindo Medical Notes"One small step for man, one large step for Makindo" |
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Related Subjects: |Ferritin |CEA |ESR |CRP |ALP |LDH |HbA1c |Alpha Fetoprotein |Neutrophil Alkaline Phosphatase |Anti-Hu ab |Anti-Yo ab |Anti-SCL70 ab |Prolactin |Liver Function Tests |Biochemical Lab values |Rheumatology Autoantibodies
🔬 Autoantibody | 🩺 Disease / Notes | 📊 Diagnostic Levels |
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🧪 Rheumatoid Factor (RF) | Antibodies against Fc fragment of IgG (IgM, IgG, IgA – usually measure IgM). • ~75% RA; 100% if extra-articular disease. • 5% healthy population. • Also in SLE, Sjögren’s, systemic sclerosis, cryoglobulinaemia, hepatitis C, sarcoidosis, malignancy. | Positive if >20 IU/mL. High titres (>60 IU/mL) = severe, extra-articular RA risk. |
🎯 Anti-cyclic citrullinated peptide (ACPA / anti-CCP) | • ~70% RA. • Much more specific than RF. • Can precede diagnosis by years. • Suggests erosive/severe RA. | Significant if >20 U/mL (lab-dependent). High titres (>60 U/mL) strongly predictive of erosive RA. |
🌙 Antinuclear Antibodies (ANA) | Non-specific autoimmunity marker. • SLE, Sjögren’s, systemic sclerosis, infections, sometimes normal. • Pattern (homogeneous, speckled, nucleolar, centromere) gives clues. | Positive if titre ≥1:80 (HEp-2). High titres (≥1:320) more likely pathological. |
🧬 Anti-topoisomerase I (Scl-70) | Diffuse cutaneous systemic sclerosis (dcSSc). | Detected by ELISA / immunoblot; no strict cut-off but strong positivity is highly specific. |
💪 Anti-Jo-1 | Polymyositis, dermatomyositis (esp. with ILD). | Positive if >20 U/mL (lab-dependent). Often high titres in active disease. |
🎯 Anti-centromere | Limited cutaneous systemic sclerosis (lcSSc, CREST). | ANA pattern: centromeric dots at titres ≥1:160 = diagnostic. |
📝 Anti-RNA polymerase I & III | Systemic sclerosis (renal crisis, diffuse cutaneous disease). | Qualitative (present/absent); high specificity. |
🔥 c-ANCA (anti-PR3) | Granulomatosis with polyangiitis (Wegener’s). | Positive if >20 U/mL. High titres correlate with active vasculitis. |
💡 p-ANCA (anti-MPO) | Microscopic polyangiitis, EGPA (Churg–Strauss). | Positive if >20 U/mL. Rising titres may suggest relapse. |
🧫 Anti-dsDNA (IgG) | SLE (specific, correlates with activity, especially lupus nephritis). | Positive if >30 IU/mL. High titres (>100 IU/mL) = strong correlation with lupus nephritis. |
💊 Anti-histone | Drug-induced lupus (e.g. hydralazine, procainamide, isoniazid). | Usually very high titres in drug-induced lupus; low titres in SLE. |
🌞 Anti-Ro (SS-A) | Sjögren’s, SLE; neonatal lupus & congenital heart block risk. | Positive if >10 U/mL. High titres increase neonatal lupus risk. |
🌙 Anti-La (SS-B) | Sjögren’s, SLE. | Positive if >10 U/mL (usually co-exists with Anti-Ro). |
🩸 Anti-β2 glycoprotein I | Antiphospholipid syndrome (thrombosis, pregnancy morbidity). | Medium/high titre = >40 GPL/MPL or >99th percentile, on ≥2 occasions ≥12 weeks apart. Low transient titres often post-infection. |