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SLE

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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

 

©Charles Gomersall, April, 2014 unless otherwise stated. The author, editor and The Chinese University of Hong Kong take no responsibility for any adverse event resulting from the use of this webpage.
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