1/5
ANCA - The Basics in 5 tweets
Anti-Neutrophil Cytoplasmic Antibodies (ANCA) positivity does not mean there is an ANCA-associated vasculitis (AAV)
ANCA negativity does not r/o AAV
Clinical context is KEY!!
ANCA - The Basics in 5 tweets
Anti-Neutrophil Cytoplasmic Antibodies (ANCA) positivity does not mean there is an ANCA-associated vasculitis (AAV)
ANCA negativity does not r/o AAV
Clinical context is KEY!!
2/5
2 STEPS involved in ANCA testing.
(1) Immunofluorescence (IF) to determine if there is staining that is cytoplasmic or peri-nuclear. Sensitive but not specific. Need to follow-up w/ antibody testing.
(2) ELISA for 2 cytoplasmic enzymes, PR3 and MPO.
2 STEPS involved in ANCA testing.
(1) Immunofluorescence (IF) to determine if there is staining that is cytoplasmic or peri-nuclear. Sensitive but not specific. Need to follow-up w/ antibody testing.
(2) ELISA for 2 cytoplasmic enzymes, PR3 and MPO.
3/5
cANCA usually points to PR3 (GrandPA, GPA, needs cPR)
pANCA usually points to MPO
cANCA usually points to PR3 (GrandPA, GPA, needs cPR)
pANCA usually points to MPO
4/5
Interpreting the tests
ANCA positive (usually pANCA) but ELISA negative -> may reflect ANY inflammatory disease (IMAD)
cANCA+, PR3 + -> likely GPA
pANCA+, MPO+ -> MPA > EGPA
ANCA +, MPO+, PR+ -> dual positivity likely levamisole
Interpreting the tests
ANCA positive (usually pANCA) but ELISA negative -> may reflect ANY inflammatory disease (IMAD)
cANCA+, PR3 + -> likely GPA
pANCA+, MPO+ -> MPA > EGPA
ANCA +, MPO+, PR+ -> dual positivity likely levamisole
5/5
ANCA like any test is ONLY one data point.
IF w/o antibody testing is not helpful.
Certain patterns may point to a specific dx but its absence cannot r/o AAV and many time ANCA IF positivity w/o ab positivity just reflects inflammation
Thoughts?
<3 @rabihmgeha
ANCA like any test is ONLY one data point.
IF w/o antibody testing is not helpful.
Certain patterns may point to a specific dx but its absence cannot r/o AAV and many time ANCA IF positivity w/o ab positivity just reflects inflammation
Thoughts?
<3 @rabihmgeha
Loading suggestions...