9 Diagnosis of autoimmune diseases Flashcards
Define sensitivity
How good the test is in identifying people with the disease.
Define specificity
How good the test is at correctly defining people without the disease.
Define positive predictive value.
The proportion of people with a positive test result who have the disease.
Define negative predictive value.
The proportion of people with a negative test who do not have the disease.
7 non-specific markers of systemic inflammation.
ESP (plasma viscosity increases in infection). CRP (liver produced, rises rapidly). Ferritin. Fibrinogen. Haptoglobin. Albumin. Complement.
What are ANAs? How are they tested for?
Anti-nuclear antibodies
Slide with antigens. Sample introduced. Second wave of fluorescently labelled antibodies matching ANA introduced.
If an ANA test is positive, which two tests come next?
Anti-ds DNA (crithidia luciliae assay, farr assay, ELISA).
ENA’s (immunoblats).
Which two antibodies are commonly found in rheumatoid arthritis? Which is more specific?
Rheumatoid factor.
Anti-CCP (ACPA). More specific. More severe disease - useful for prognosis.
What is the main target antigens of cytoplasmic ANCA?
PR3 (90%).
What is the main target antigen of perinuclear ANCA?
MPO (70%).
Which three conditions are ANCA found in?
ANCA associated systemic vasculinities (AASV):
Wegner’s granulomatosis.
Microscopic polyangitis.
Churg-Staruss syndrome.
What use is ANCA in ANCA associated systematic vasculitides? (3).
Suggestive of diagnosis.
Return during -ve period may suggest flare.
Presence without clinical signs doesn’t signal treatment need.
What antibodies are found in primary biliary sclerosis?
Anti-mitochondrial Ab.
Which antibodies are found in autoimmune hepatitis?
Anti-smooth muscle and anti-liver/kidney/microsomal.
What course do autoantibodies take in Type 1 Diabetes Mellitus?
Initially increase with destruction of pancreas but disappear with progression and total destruction of beta islet cells.
