Gout
Also known as: gouty arthritis, podagra
An inflammatory arthritis caused by deposition of uric acid crystals in joints, triggered when blood urate is persistently high.
Overview
Uric acid is a waste product of purine metabolism. When its level exceeds saturation it crystallises in cool joints, classically the big toe, and the crystals provoke a sudden, exquisitely painful attack. Repeated attacks damage joints and form lumps (tophi). Lowering urate with medication dissolves the crystals and prevents attacks.
Causes
- Reduced kidney excretion of urate (90%)
- Overproduction: high purine diet, cell breakdown, rare enzyme defects
Risk factors
- Male sex, age
- Obesity, metabolic syndrome
- Alcohol (beer and spirits), sugary drinks, red meat and shellfish
- Diuretics and low-dose aspirin
- Chronic kidney disease
- Family history
Symptoms
What a clinician may find
- A red, hot, shiny, extremely tender joint, often the first metatarsophalangeal joint
- Tophi on the ears, fingers and elbows in chronic gout
Complications
- Joint damage and tophi
- Kidney stones
- Association with heart disease and kidney disease
Diagnosis
Crystals seen in joint fluid confirm it; a raised serum urate supports it (but may be normal during an attack); ultrasound or dual-energy CT shows crystal deposits. Infection must be excluded in a single hot joint.
Treatment
Attacks: NSAIDs, colchicine or steroids, started early; rest and ice. Prevention: allopurinol (or febuxostat) started after the attack settles and titrated to a target urate, with cover against flares for the first months; weight loss and diet changes.
Prevention
Healthy weight, limit alcohol and sugary drinks, moderate red meat and seafood, stay hydrated, review diuretics.
When to seek care
Same-day assessment for a hot swollen joint with fever, since septic arthritis looks identical and is an emergency.