diagnostic Flashcards
proportion of patients w/ positive test results who are correctly diagnosed
positive predictive value
what is the current “gold standard” for testing?
indirect immunofluorescence ANA assay
what makes for a high negative predictive value?
low disease prevalence because if you have a small amount of people that actually have the disease then the number of negative tests that you have are more likely to be correct
what are the acute phase reactants?
ESR, CRP, ferritin, fibrinogen, plateletys
what is Antineutrophilic cytoplasmic antibody (ANCA) good for?
really only vasculitis
complement tends to be _____ in chronic autoimmune and inflammatory states?
reduced
when is ESR most helpuful?
when it is normal so you can rule people out
let’s say the RF is negative what does that mean?
you may need to test again because if they arent having an acute flare the body may not be producing IgM
is ANA used to monitor disease activity?
no
anti-RNP is used for what?
SLE and mixed connective tissue disease
percentage of patients w/ the disease who have a positive result
sensitivity
probability of correctly identifying a patient WITH a disease
sensitivity
percentage of patiens w/o disease with negative test result
rare false positives
most useful when positive
specificity
C3 and C4 are useful in monitoring?
SLE patients
ANA is has high ____ but low ____
sensitivity, specificity
ANA tests
1:80
anti-SM or smith is specific for what?
SLE
what is rheumatoid factor?
IgM autoantibody directed against the Fc (heavy chain) portion of the IgG
what is the diagnostic test for lupus?
anti-dsDNA
rare false negative, but increased false positives
sensitivity
anti-Ro (SS-A) and anti-La (S-B) are used for what?
SLE or Sjogren’s (especially for SICCA?) dry eyes and dry mouth
anticentromere antibodies is seen in what?
cleroderma specifically the CREST variant
probability of correctly identifying a patient without the disease
specificity
anti-dsDNA does not occur in ___?
drug induced lupus except for
- penicillamine
- minocycline
- antitumor necrosis factor
anti-Ro and anti-La are important for mother’s why?
because the child can have neonatal cutaneous lupus that leads to complete heart block
number of new diagnoses that have occured in a specific time interaval in a specific population
incidence
what is the anti-CCP good for?
highly specific for RA, better than RF for RA, but together (RF-anti-CCP) almost 100% they have RA
