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CNSLF Path - Laboratory Dx of Connective Tissue Disorders (ii) (Systemic…
CNSLF Path - Laboratory Dx of Connective Tissue Disorders (ii)
Systemic Lupus Erythematosus (SLE)
most common CTD
inflamm multisystem disease
unknown aetiology
diverse clinical + lab abnormalities
variable course + prognosis
some benign (skin rash + joint pain)
some can cause death
multiple autoabs
cytotoxic function
ICD
Type 2 hypersensitivity
reduces no of blood cells (immune cytopenias common)
haemolytic anaemia
neutropenia
thrombocytopenia
anaemia of chronic disease
Type 3 hypersensitivity
due to ICD
renal disease
skin disease
vasculitis
F>M 9:1
peak age: 2nd + 3rd decade
incidence varies a lot even in 1 country (e.g. difference states in US)
US prevalence = 15-50/100 000 (now estimated to be 1 in 1000)
racial variation - more frequent + severe in African-Americans compared to Caucasians
genetic associations: C4A null alleles (complement important for disposing of immune complexes)
inflamm of any organ, predominantly...
skin
joints - arthritis
kidneys
brain - cerebral disease
serosal surfaces (serositis)
pleural
pericardium
causes pleural/pericardial effusions
peritoneum uncommonly (peritonitis v rare)
butterfly rash
not always obvious
over bridge of nose
usually become more prominent with sun
Discoid lupus erythematosus (DLE)
most common chronic form of cut lupus
persistent scaly slightly raised disc-like plaques on scalp, face + ears
may cause pigmentary changes, scarring + hair loss
not itchy of sore but may scar
rashes in SLE often photosensitive
immunofluorescence: lupus band @ dermo-epidermal junction, granular so you know its ICD
oral ulcers
Renal
FSGN
focal prolif GN
diffuse prolif GN
membranous GN
sclerosis
increased creatinine
blood + protein in urine
glom will be +ve in immunofluorescence
Subtypes
neonatal
abs cross placenta
causes congenital heart block in baby (rare, 1/3 of babies with congenital heart block are born to mother with known SLE, 1/3 to mother with undated She, 1/3 idiopathic)
end stage
active inflamm over (no need for immunosuppression)
have to live with comps (stroke, renal failure)
latent
APS
classical
drug-induced
morbidity + mortality: organ damage, effects of immunosuppression
common autoabs
ANF
anti-dsDNA (+ve in >95% of untxed lupus)
ENAs
SM (specific but only 30% sensitive)
Ro (also in Sjogrens)
La (also in Sjogrens)
abs against RBCs, WBCs, platelets
Dx
clinical hx + exam
urinalysis + urine microscopy
abs
assess function of potentially involved organs
monitoring disease activity
function of affected organs
FBC
Complement (high consumption causes low C3 + C4 - active disease)
anti-dsDNA
CRP may be a poor guide to inflamm, ESR instead
can have a poor outlook without tx
hormonal influence: can have flares during/after pregnancy