Diagnosis of autoimmune disease

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  • Created by: hadar
  • Created on: 26-02-18 10:45
Describe the clinical presentation of scleroderma (diffuse systemic sclerosis)
SOB on exertion, pulmonary fibrosis, fatigue, aches and pains, sclerodactyly, skin changes-thickening,livedo reticularis
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What tests are required to confirm autoimmune disease of scleroderma?
ANA, ANCA, CK, Rheumatoid factor, anti-CCP antibody, complement, FBC, U&E, LFT, CRP
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When should diagnostic testing be used?
Diagnostic tests should be used to answer specific questions and/or to support a clinical diagnosis, but not as screening tools
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What is sensitivity?
[a/(a+c)] measure of how good the test is in identifying people with the disease a=True positive c= False negative
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What is specificity?
measure of how good the test is at correctly defining people without the disease b= False positive d= True negative
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What is positive predictive value?
[a/(a+b)] The proportion of people with a positive test who have the target disorder
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What is negative predictive value?
d/(c+d) The proportion of people with a negative test who do not have the target disorder.
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What are the 2 main types of diagnostic tests?
1) non specific- e.g. inflammatory markers 2)disease specific- e.g. autoantibody testing/ HLA typing
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List 7 non-specific markers of systemic inflammation
1)ESR 2)CRP 3)ferritin 4)fibrinogen 5)haptoglobin 6)albumin 7)complement
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What are antinuclear antibodies (ANA)?
Antibodies in the patient’s blood that bind to the cell nucleus
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How would you detect for anti-dsDNA?
1)Crithidia luciliae assay (protosoa) 2)Farr assay 3)ELISA
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How would you detect for ENA's?
1)Immunoblots 2)Individual ELISA’s 3)Combination of antigens
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How would you detect for ANA?
indirect imunofluoresence
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What is in an ANA screen?
dsDNA • Chromatin • Ribosomal Protein • **-A (52 and 60) • **-B • Sm • Sm/RNP • RNP (A and 68) • Scl-70 • Jo-1 • Centromere B
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What antibody is associated with SLE?
dsDNA or sm
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What antibody is associated with sjogrens syndrome?
La
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What antibody is associated with neonatal lupus erythematous?
Ro
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What antibody is associated with diffuse systemic sclerosis?
scl-70
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What antibody is associated with limited systemic sclerosis?
centromere
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What antibody is associated with polymyositis?
Jo-1
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What antibody is associated with dermatomyositis?
Mi-2
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What antibody is associated with rheumatoid arthritis?
CCP
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What antibody is associated with diffuse glomerulonephritis?
dsDNA
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What antibody is associated with membranous glomerulonephritis?
Sm or Ro
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What antibody is associated with neonatal heart block?
Ro
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What antibody is associated with raynauds phenomenon?
U1-RNP
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What antibody is associated with fibrosing avleolitis?
Jo-1 or U1-RNP
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What antibody is associated with erosive joint damage?
CCP
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What is the Anti-dsDNA autoantibody against and the clinical association?
dsDNA- highly specific for SLE
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What is the Anti-Sm/ Anti-RNP autoantibody against and the clinical association?
Smith/ proteins containing U1-RNA- highly specific for SLE, RA, scleroderma, sjogre syndrome, MCTD
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What is the Anti-SSA (Ro) autoantibody against and the clinical association?
RNPs- sjogren syndrome, SLE, neonatal lupus
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What is the Anti-SSB (La) autoantibody against and the clinical association?
RNP's- sjogren syndrome, SLE, neonatal SLE
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What is the Anticentromere autoantibody against and the clinical association?
centromere/kinetochore region of chromosome- limited scleroderma, pulmonary hypertension, primary biliary cirrhosis
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What is the Anti-scl 70 autoantibody against and the clinical association?
DNA topoisomerase I- diffuse scleroderma
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What is the Anti-Jo1 autoantibody against and the clinical association?
Histidyl tRNA synthetase- inflammatory myopathies with intestinal lung disease, fever, arthritis
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What is the Anti-SRP autoantibody against and the clinical association?
antibody to signal recognition protein- inflammatory myopathies with poor prognosis
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What is the AntiPM/scl autoantibody against and the clinical association?
antibody to nucleolar granular component- PM/ scleroderma overalp syndrome
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What is the Anti-Mi2 autoantibody against and the clinical association?
antibodies to nucleolar antigen of unknown function- DM
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What are the clinical features of rheumatoid arthritis?
joint stiffness and pain - stiffness worse in morning an improves over the ay
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What does the X-ray show in rheumatoid arthritis?
peri-articular swelling with effusion of MCP joints, osteopenia, joint space narrowing and erosion
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What is rheumatoid factor?
Antibody (IgM, IgG or IgA) directed against the Fc portion of IgG Commonly found in rheumatoid arthritis but not diagnostic of the diseases (sensitivity and specificity around 70%) Can be seen with other diseases in polyclonal stimulation B-cells
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What is anti-CCP antibody (ANPA)?
ACPA more specific (95%) for RA then RF Similar sensitivity to RF Useful prognostic marker ACPA positive patients tend to have more severe and erosive disease
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When is ANCA ordered?
when concerned that patient has vasculitis
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What is the clinical presentation of granulomatosis with polyangitis/ Wegeners granulomatosis??
fever, fatigue, muscle pain, night sweats, weight loss, urine contains blood, lung granuloma formation on CXR, raised creatinine and urea
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Describe cytoplasmic (c)ANCA
Granular fluorescence of neutrophil cytoplasm with nuclear sparing- targets antigens PR3 mainly and MPO
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Describe perinuclear (p)ANCA
Apparent fluorescence of the nucleus only- targets MPO mainly and PR3
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What is the difference between ANCA and PR3/MPO?
ANCA is the pattern and anti-PR3/MPO is the autoantibody causing the pattern
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What is the clinical utility of ANCA testing?
+ve ANCA useful in diagnosis not gold standard- -ve ANCA doesnt exclude AASV- Persistence of ANCA in absence clinical indications active disease doesnt indicate need for continued treatment- Reemergence ANCA +ve in ANCA -ve in remission suggest flare
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What test would you do for primary biliary sclerosis?
Anti-mitochondrial Ab specific for primary biliary sclerosis
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What test would you do in autoimmune hepatitis?
Anti-smooth muscle and anti-liver/kidney/microsomal (LKS) Abs, found in autoimmune hepatitis
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What antibodies are found in Type I DM?
Non-pathogenic Several types: islet cell antibodies anti-GAD65 anti-GAD67 anti-insulinoma antigen 2 (IA-2) insulin autoantibodies (IAAs) Disappear with progression of disease and total destruction of β islet cells
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What is the role of autoantibodies in diagnosis of type I DM?
Disease confirmation to identify relatives and patients at risk of developing autoimmune diabetes Negative predictive value of ICA and IAA is almost 99% Increased risk of disease development with greater number of different autoantibodies present
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Card 2

Front

What tests are required to confirm autoimmune disease of scleroderma?

Back

ANA, ANCA, CK, Rheumatoid factor, anti-CCP antibody, complement, FBC, U&E, LFT, CRP

Card 3

Front

When should diagnostic testing be used?

Back

Preview of the front of card 3

Card 4

Front

What is sensitivity?

Back

Preview of the front of card 4

Card 5

Front

What is specificity?

Back

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