Autoimmunity diagnosis Flashcards

1
Q

Define Sensitivity

A

Measure of how good a test is in identifying people with the disease

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2
Q

Define Specificity

A

Measure of how good a test is at correctly defining people without the disease

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3
Q

What are positive & negative predictive values?

A
\+ve= proportion of people with a positive test who have the target disorder
-ve= proportion of people with a negative test who do not have the target disorder
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4
Q

What types of diagnostic tests are there?

A
  • Non specific: inflammatory markers

- Disease specific: HLA typing, autoantibody testing

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5
Q

Name some non-specific markers of systemic inflammation

A
  • ESR
  • CRP
  • Ferritin
  • Fibrinogen
  • Haptoglobin
  • Albumin
  • Complement
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6
Q

What is ANA?

A
  • Antinuclear antibodies

- Detection by fluorescence

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7
Q

What is rheumatoid factor?

A
  • Antibody (IgM, IgG, IgA) directed against the Fc portion of IgG
  • Commonly found in rheumatoid arthritis
  • Not diagnostic of the diseases
  • High titters may be pathogenic in vasculitis
  • Can be seen with other diseases in which polyclonal stimulation of B cells is seen
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8
Q

What is anti-CCP can any alternatives be used?

A
  • Blood test
  • ACPA more specific for RA then RF
  • Similar sensitivity to RF
  • Useful prognostic marker
  • ACPA positive patients tend to have more severe erosive disease
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9
Q

What does ANCA stand for?

A

Anti-Neutrophilic Cytoplasmic Antibodies

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10
Q

Describe autoimmune liver disease

A
  • Anti-mitochondrial Ab specific for primary biliary sclerosis
  • Anti-smooth muscle & anti-liver/kidney/microsomal
  • Abs found in autoimmune hepatitis
  • Antibodies detected by IF screening & antigen specific ELISA
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11
Q

What is autoantibodies in Type I diabetes mellitus?

A
  • Non-pathogenic
  • Several types: islet cell antibodies, anti-insulinoma antigen, anti-GAD(65, 67), insulin autoantibodies
  • Disappear with progression of disease & total destruction of β islet cells
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12
Q

What is the role of autoantibodies in diagnosis of type I diabetes mellitus?

A
  • Disease conformation
  • Identify relatives & patients at risk of developing autoimmune diabetes
  • Negative predictive value ICA & IAA
  • Inc risk of disease development with greater number of different autoantibodies present & younger age of patient
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13
Q

What is the future of diagnostic testing in autoimmune diseases?

A
  • Cytokines determination in serum
  • Detection of antigen specific autoimmune T & B cells
  • Measure of therapeutic response
  • Personalised medicine, genetic profiling to determine individual risk of the disease
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