GOUT Flashcards
Features of crystal arthritis
- Crystal Arthritis is the commonest cause of acute joint swelling
- Gout most common in men
- Pseudogout in women
- Easy to diagnose and treat
- Miserable for patients
Gout features
- Caused by the deposition of monosodium urate crystals within joint
- The immunological reaction initiated to try and remove them, leads to acute pain and swelling
- Only ‘Curable’ form of inflammatory arthritis
Epidemiology of gout
UK General Practice Research Database – prevalence 1.4% (1999)
7.3% of men aged >75yrs
Overall male : female ratio 5:1
Hyperuricaemia much more common – affects 15% population
Gout prevalence increases with age
Pathogenesis of Gout
Under exretion urate + overproduction urate >
Hyperuricaemia >
Crystal formation & shedding >
Synovial cells > Inflammatory response
What causes under excretion urate in gout
Genetics
Drugs
CKD
Diuretics
Lead toxicity
What causes overproduction of urate in gout
Diet
Alcohol
Metabolic proliferation
Obesity
Psoriasis
Purine rich diet
Causes of Gout
Alcohol - mostly beer
Red meat, shellfish, offal
Soft drifts
Psoriasis
Haematological malignancy
Essential risk factors for Gout
Renal impairment
Beer
Diuretics
Aspirin
Family History
Fructose
Elderly
Men
Impaired renal function
Clinical features of Gout
- Acute episodes
- Onset often at night
- Resolve spontaneously (quicker with treatment)
- Usually recur in a predictable pattern of joint involvement
Typical joints that gout affects
- 1st MTPJ 90%
- Midfoot, ankle, knee, wrist, elbow hand
- Periarticular involvement
- Olecranon bursitis
- Systemic features can occur
Differntial diagnosis for Gout
Septic Arthritis
Trauma
Pseudogout
Rheumatoid Arthritis
(Osteoarthritis!)
Investigations for Gout
FBC (expect raised WCC)
U+E
LFT if concern re alcohol
Serum Uric Acid (often normal during acute attack)
CRP
Xray if recurrent episodes or concern re sepsis
Joint aspiration
Joint X ray
4 clinical phases of gout
asymptomatic hyperuricemia,
acute/recurrent gout,
intercritical gout,
chronic tophaceous gout
Acute treatment of Gout
Explain the disease
Advice about lifestyle - alcohol diet weight loss fluid intake
NSAID (short course) unless:
Renal failure
Peptic Ulcer Disease
Some pts with asthma
Colchicine
500ug 2-3 times daily
Corticosteroids
Intra-articular
Oral - low dose (5-10mg short course)
Ice packs
Indication of chronic gout
- Recurrent attacks
- Evidence of tophi or chronic gouty arthritis
- Associated renal disease
- Normal serum Uric acid cannot be achieved by life-style
modifications
Medications for chronic gout
- Allopurinol – Xanthine Oxidase Inhibitor
- Febuxostat – more potent Xanthine Oxidase Inhibitor
- Benzbromarone / Probencid – if allergic / intollerant
Complications of Gout
Disability and misery
Tophi
Renal disease:
Calculi 10 -15%
Chronic urate nephropathy
Acute urate nephropathy (cytotoxics
Gout pathophysiology
Uric acid has limited solubility in the blood.
When there is too much uric acid in the blood, it can become a urate ion and bind sodium, leading to the formation of monosodium urate crystals
which deposit in areas with slow blood flow, including joints and kidney tubules.
Signs of Gout
Joint inflammation
Gouty tophi
Symptoms of Gout
- Red, tender, hot, and swollen joint.
- Joint stiffness
- Rapid onset severe joint pain
Complications of Gout
Urate nephrolithiasis: there is an association between gout and urate renal stones due to hyperuricaemia
What is pseudogout?
Pseudogout is a form of inflammatory arthritis caused by deposition of calcium pyrophosphate crystals in the synovium.
Pseudogout epidemiology
Mostly women
Most patients affected by acute pseudogout are over the age of 65
RF for pseudogout
- Increasing age: the greatest known risk factor for pseudogout
- Previous joint trauma
- Hyperparathyroidism
- Haemochromatosis
- Acromegaly
- Wilson’s disease
- Hypomagnesaemia
- Hypophosphataemia
Pathophysiology of pseudogout
The deposition of calcium pyrophosphate crystals is thought to trigger synovitis, with the knee, shoulder, and wrist being most commonly affected.
Acute pseudogout
Acute - mainly affects larger joints in the elderly and is usually spontaneous but can be provoked by illness, surgery or trauma
Chronic Pseudogout
Chronic - inflammatory RA-like symmetrical polyarthritis and synovitis
Signs of Pseudogout
Very similar to gout and usually indistinguishable until joint aspiration is performed.
- Joint inflammation: pain, erythema and swelling
- Signs can be monoarticular (1 joint) or polyarticular (several joints)
Symptoms of Pseudogout
- Rapid onset severe joint pain: knee, shoulder and wrist are most commonly affected
- Joint stiffness
Primary investigations for pseudogout
- Joint aspiration:weakly-positively birefringent rhomboid-shaped crystals under polarised microscopy confirm the diagnosis. If any bacterial growth, then patient is likely to have septic arthritis
-
Joint X-ray:chondrocalcinosis (calcification of articular cartilage) is seen in 40% of casesand is highly suggestive of pseudogout but is not diagnostic; theabsenceof chondrocalcinosis doesnotexclude pseudogout
In the knee, this is seen as linear calcifications of the articular cartilage and meniscus
Investigating the underlying cause for pseudogout
Usually only done in young patients:
- Serum bone profile and PTH: investigate for hyperparathyroidism and hypophosphataemia
- Iron studies: investigate for haemochromatosis
- Serum magnesium: investigate for hypomagnesaemia
DD for pseudogout
- Gout
- Septic arthritis
- Rheumatoid arthritis
- Osteoarthritis
Acute management for Pseudogout
- Anti-inflammatory:NSAIDs or colchicine, particularly in polyarticular disease
- Corticosteroid:intra-articularsteroids can be used in monoarticular disease orsystemicsteroids in polyarticular disease
- Cool packs and rest
- Aspiration of the joints - relieves pain
Chronic management for Pseudogout
- DMARDs: e.g. methotrexate and hydroxychloroquine may be considered in chronic pseudogout
- Joint replacement: only indicated in chronic, recurrent cases with severe joint degeneration
Prognosis Pseudogout
Resolution usually happens within a few days of treatment but some can become chronic
Gout X ray
JOint space maintained
Lytic lesions in bone
Punched out erosions
Erosions can have sclerotic borders
