9 Diagnosis of autoimmune diseases Flashcards

1
Q

Define sensitivity

A

How good the test is in identifying people with the disease.

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2
Q

Define specificity

A

How good the test is at correctly defining people without the disease.

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3
Q

Define positive predictive value.

A

The proportion of people with a positive test result who have the disease.

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4
Q

Define negative predictive value.

A

The proportion of people with a negative test who do not have the disease.

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5
Q

7 non-specific markers of systemic inflammation.

A
ESP (plasma viscosity increases in infection).
CRP (liver produced, rises rapidly).
Ferritin. 
Fibrinogen.
Haptoglobin.
Albumin.
Complement.
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6
Q

What are ANAs? How are they tested for?

A

Anti-nuclear antibodies

Slide with antigens. Sample introduced. Second wave of fluorescently labelled antibodies matching ANA introduced.

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7
Q

If an ANA test is positive, which two tests come next?

A

Anti-ds DNA (crithidia luciliae assay, farr assay, ELISA).

ENA’s (immunoblats).

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8
Q

Which two antibodies are commonly found in rheumatoid arthritis? Which is more specific?

A

Rheumatoid factor.

Anti-CCP (ACPA). More specific. More severe disease - useful for prognosis.

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9
Q

What is the main target antigens of cytoplasmic ANCA?

A

PR3 (90%).

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10
Q

What is the main target antigen of perinuclear ANCA?

A

MPO (70%).

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11
Q

Which three conditions are ANCA found in?

A

ANCA associated systemic vasculinities (AASV):

Wegner’s granulomatosis.
Microscopic polyangitis.
Churg-Staruss syndrome.

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12
Q

What use is ANCA in ANCA associated systematic vasculitides? (3).

A

Suggestive of diagnosis.
Return during -ve period may suggest flare.
Presence without clinical signs doesn’t signal treatment need.

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13
Q

What antibodies are found in primary biliary sclerosis?

A

Anti-mitochondrial Ab.

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14
Q

Which antibodies are found in autoimmune hepatitis?

A

Anti-smooth muscle and anti-liver/kidney/microsomal.

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15
Q

What course do autoantibodies take in Type 1 Diabetes Mellitus?

A

Initially increase with destruction of pancreas but disappear with progression and total destruction of beta islet cells.

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16
Q

Which four autoantibodies are found in type 1 DM?

A

islet cell antibodies
anti-GAD65 , anti-GAD67
anti-insulinoma antigen (IA-2)
insulin autoantibodies (IAAs)

17
Q

What is the role of autoantibodies in diagnosis of Type 1 DM?

A

Disease confirmation. -ve predicave value of 99%. Help identify relatives. Increased risk with greater variety of autoantibodies at younger age.