|
| |
Systemic
lupus erythematosus
Chronic autoimmune disease which produces symptoms varying from mild to
life-threatening. Characteristically affects young women but all ages can be
affected. Most distinct immunological abnormality is the presence of
autoantibodies. Anti-nuclear antibodies to native double-stranded DNA are
diagnostic. Course of the disease is characterised by periods of remission and
relapse.
Epidemiology
- prevalence 4-280 cases/100 000. Highest in Afro-Caribbeans, followed by
Asians
- male:female = 1:13
- disease onset 16-55 years
- blacks have a worse prognosis
Clinical features
- Constitutional symptoms (very common): fatigue, fever, weight loss
- Joints: athritis and arthralgia in 95%. Usually non-deforming
- Skin: involved in 80%.
- Renal:
- about 50% develop urinary or functional renal abnormalities but virtually
all patients have histological abnormalities
- proteinuria is most common abnormality, usually presenting within the first
5 years of diagnosis
- renal biopsy useful in differentiating lupus nephritis from other causes of
renal abnormalities such as infection but more importantly it determines
precise histology and therefore likely response to therapy. Generally
performed on all patients with haematuria/proteinuria or a fall in creatinine
clearance
- Pulmonary:
- pleuritic chest pain extremely common. May be due to a serositis in which
case may be accompanied by a pleural rub or an effusion. Pulmonary embolus and
infarction need to be excluded in view of the increased risk in patients with
SLE
- pneumonia
- acute lupus pneumonitis
- uncommon
- no specific clinical characteristics distinguish it from pneumonia
and it is essential to rule out infection
- clinical features include fever, dyspnoea and hypoxia
- CXR: alveolar infiltrates - usually basal
- biopsy may be helpful in distinguishing it from pneumonia
- pulmonary
haemorrhage
- rare overall but not uncommon in those patients requiring ICU
admission
- clinical features: dyspnoea, severe hypoxia, sudden drop in
haemoglobin, haemoptysis (not invariable)
- treatment: pulsed methylprednisolone, pulsed cyclophosphamide and
plasma exchange
- pulmonary hypertension
- 17-40% of unselected patients with SLE
- more common in patients with Raynauds
- not responsive to corticosteroids except in the rare patients in
whom it is due to an arteritis
- Cardiovascular:
- innocent systolic murmurs and mild pericarditis are frequent
- diastolic murmurs are indicative of Libman-Sachs endocarditis:
- due to an
accumulation of inflammatory material and thrombus
- embolic risk
- increased risk of coronary disease
- hypertension; often causes deterioration in renal function
- Haematological
- normochromic, normocytic anaemia common (anaemia of chronic disorders)
- haemolytic anaemia in 25%
- leucopaenia common with a reduction in both granulocytes and lymphocytes
- thrombocytopaenia common; usually due to anti-platelet antibodies. Spleen is
major site of destruction
- lymphadenopathy occurs especially during exacerbations
- Neuropsychiatric:
- spectrum of disease varies from purely functional to completely organic
(differential includes steroid psychosis)
- seizures occur in 15%. Metabolic abnormalities and other secondary causes
need to be excluded but often no specific abnormality is found
- peripheral neuropathy in around 10%
- aseptic meningitis (differential includes NSAID-induced aseptic
meningitis)
- CVAs and transverse myelitis occur secondary to vasculitis or
thromboembolism
- transverse myelitis may respond to combination of pulsed
methylprednisolone and pulsed cyclophosphamide
- diagnosis of cerebral lupus is difficult because there may be little
correlation to disease activity elsewhere
Diagnosis
Think of SLE in patients (especially young females) with any of the
following:
- photosensitivity
- arthralgia or rash
- Raynaud's or mouth ulcers
- pleurisy
- proteinuria
- haematological abnormalities (especially low white cell count or
thrombocytopaenia)
- abortion (recurrent, midtrimester)
- any neurological abnormality (including seizures)
- fatigue or depression
Investigations
Initial screening
- FBC and differential
- ESR/CRP. Obviously there are few patients in ICU in whom the ESR will be
normal but the combination of a high ESR with a low CRP is highly suggestive of
SLE. NB In the presence of co-existing infection CRP will also be raised
- anti-nuclear antibodies: screening test of choice. Positive in virtually all
cases of SLE
If ANA positive:
- double stranded DNA: although specific not positive in all patients with SLE
- anti-Ro, anti-La, anti-RNP or anti-Sm are less specific
- tests for anti-phospholipid syndrome
- complement (C3, C4)
- +/- renal biopsy
Screen for infection as this often precipitates or accompanies disease flares
Treatment
- supportive
- specific:
- corticosteroids: mainstay of therapy
- cyclophosphamide: used for life-threatening conditions (vasculitis, renal
disease, severe thrombocytopaenia, disease-induced leucopaenia and anaemia).
Trend towards pulse therapy as this allows effective use of Mesna to prevent
haemorrhagic cystitis
- azathioprine: generally used for maintenance regimes to allow a reduction
in steroid dose
- therapy of renal disease is a specialist area with a variety of
immunosuppressive regimes under investigation
- IV gamma globulin effective short term therapy for thrombocytopaenia
© Charles Gomersall December 1999
|
