SLE - Systemic Lupus Erythematosus
SLE (Systemic Lupus Erythematosus) is an
autoimmune connective tissue disease, similar to
systemic sclerosis, RA, and mixed connective tissue disease. Often, symptoms of these diseases overlap. In cases where you unable to distinguish exactly which condition is present,we would normally say that
mixed connective tissue disease is present. Like those other disorders, ANA’s (anti-nuclear antibodies) can be found in blood of many affected patients.
The four key features of Connective Tissue disease:
- Inflammation
- Fibrosis / scarring
- Vasospasm (including Reynaud’s Syndrome)
- Vascular Thrombosis
The main clinical features, and organ complications associated with connective tissue disease can often be put down to one of the above pathological mechanisms.
There are also specific types of antibody that are more readily associated with the different types of connective tissue disease.
Epidemiology
- Prevalence is roughly 1 in 4000
- About 10x more common in women!
- 2-3x more common in Indian Asians than Caucasians
- 5x more common in black Africans than in Caucasians
- Can present at any age
- Peak incidence is between 25-35
- Second peak of incidence is between 50-60
Aetiology
- Strong genetic disposition
- Family members 50x more likely to have the disease than members of the general population
- UV light exposure thought to increase the risk
- Drugs
- Chlorpromazine, hydralazine, isoniazid
Clinical features
Photosensitive rash – can occur anywhere on the body, but typically seen on the face – as this area is most likely to be exposed to the sun!
Nonspecific symptoms
- General malaise
- Fatigue
- Low-grade fever
- Weight loss
- Alopecia
- Mucosal ulceration – particularly in the mouth
Vascular Changes
- Nail edge infarcts
- Splinter haemorrhages
Arthritis - Usually:
- Symmetrical
- Small joints
- Polyarthritis
- The arthritis is non-erosive, and thus the joint is permanently damadged, but there may be ligament damage, which can cause deformities similar to rheumatoid arthritis. However, unlike in RA, the deformities are reducible, and they should not affect joint function – e.g. the patient should be able to make a fist.
Systemic involvement
- Nephrosis – anti DNA antibodies are toxic to the kidney
- You should always do a urine dipstick on any patient you suspect with SLE! If there is nephro damage it will show up as excess protein on dipstick! – there will also possibly excess blood.
Nervous system involvement
Diagnosis
According to the American College of Rheumatology (ACR), for a patient to be diagnosed with SLE, they must fulfil 4 of the following 11 criteria:
Malar Rash
Oral ulceration
Discoid Rash – a round or oval rash seen on areas of skin exposed to sunlight
Arthritis
Photosensitivity
Serositis
Neurological disorders
Renal disorder
- Proteinuria (>0.5g/day)
- Red cell casts in urine
Haematological disorder
- Leucopenia
- Lymphopenia
- Haemolyitc anaemia
- Thrombocytopaenia
Immunological disorder
- Antibodies to double stranded DNA
- Anti-Sm antibodies
ANA positive
Investigations
- Urine dipstick – increased protein, red cell casts
- Blood – anaemia, thrombocytopenia, leukopenia, lymphpaenia, raised ESR and CRP.
- ANA testing – positive in 90% of patients. Concentration of antibodies does not reflect the severity of the disease.
- Antibodies to doublestranded DNA (dsDNA)– highly specific for SLE – but only present in 60% of cases. In some patients, the concentration of the antibodies may reflect the severity of the underlying disease
Complications
- Increased incidence of atherosclerotic disease
- Increased risk of thrombosis
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