When (and how) to do a 'vasculitis screen'
Rob Hunter | @renalrob
GIM teaching | 2nd August 2024
Slides created with xaringan.
Overview
some cases
clinical features of vasculitis
what is a 'vasculitis screen'
what is a 'renal screen'
ANCA testing
slides at: www.kidneyfish.net/talks/
Case 1
23M unwell for 4 months:
[ details redacted for online slide ]
[ was a case of IgAV ]
Chapel Hill Consensus
Case 2
85F unwell for 9 months:
[ details redacted for online slide ]
[ was a case of AAV with ENT, nerve, skin and kidney disase ]
Questions
what is the differential diagnosis?
what tests would you do?
Questions
what is the differential diagnosis?
what tests would you do?
if she is ANCA +ve, what is the probability that this is vasculitis?
if she is ANCA -ve, what is the probability that this is vasculitis?
ANCA seropositivity in 1 in 300 blood donors (c.f. 1 in 6 for ANA).
Pre-test probability if sinus and GN = 0.3.
ANCA vasculitis
ANCA false positives
Investigations in suspected vasculitis
'Renal screen'
Consider:
- look closely at routine tests / previous trends
- PR3, MPO, GBM
- C3, C4
- ANA, ENA, dsDNA
- paraprotein screen, immunoglobulins
- HepB, HepC, HIV
- CK
- blood film, haemolysis screen
'Renal screen'
Trak options:
- vasculitis screen = ANA, PR3, MPO, C3, C4
- connective tissue screen = ANA, DNA, ENA, C3, C4, CCP
- autoimmune profile = ANA, DNAIF, GPC, AMA, SMA, TPO
- glomerulonephritis = vasculitis screen + GBM + ENA screen
(ENA = Ro, La, SmDP, U1RNP, Scl70S, Jo1)
Take-home messages
there is no catch-all 'renal screen'
test for vasculitis if there is a reasonably high pre-test probability
send PR3, MPO (+/- GBM) and phone immunology labs
ANCA not 100% sensitive or specific
indications include: suspected GN, ENT disease, alveolar haemorrhage, pulmonary nodules, scleritis, neuropathy, rash with systemic features
if suspecting vasculitis (or intrinsic renal disease) then ask renal
slides at: www.kidneyfish.net/talks/