Crystal arthritis Flashcards
Define Gout
Gout is a syndrome characterised by: hyperuricaemia and deposition of urate crystals causing attacks of acute inflammatory arthriti
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 excretion 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
What affects renal clearance of uric acid
Renal impairment (any cause)
Drugs
Low dose aspirin reduces renal clearance by 10%
Diuretics – worse with higher dose
Cyclosporin, TB drugs, theophyllines
Genetics – affects renal clearance of uric acid
Fructose – shares renal uric acid transporter
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% metatarsophalangeal joint
Midfoot, ankle, knee, wrist, elbow hand
Periarticular involvement
Olecranon bursitis
Systemic features can occur
Differntial diagnosis for Gout
Septic Arthritis
Trauma
Calcium Pyrophosphate Arthritis
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
1️⃣asymptomatic hyperuricemia,
2️⃣acute/recurrent gout,
3️⃣intercritical gout,
4️⃣chronic 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 NSAID
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
Pathway of gout
Asymptomatic hyperuricaemia
Acute gout
Inter critical gout
Chronic tophaceous gout
Acute clinical features of gout
- swelling
- erythema
- shiny overlying skin
1st line investigation for gout
Joint aspiration and polarised light microscopy
