Gout and pseudogout Flashcards
What is gout?
Gout is a type of crystal arthropathy associated with chronically high blood uric acid levels.
Urate crystals are deposited in the joint causing it to become hot, swollen and painful.
What are gouty trophi?
Gouty tophi are subcutaneous deposits of uric acid typically affecting the small joints and connective tissues of the hands, elbows and ears.
Differential diagnosis for gout
The obvious and extremely important differential diagnosis is septic arthritis.
Risk factors for gout
- Male
- Obesity
- High purine diet (e.g. meat and seafood)
- Alcohol
- Diuretics
- Existing cardiovascular or kidney disease
- Family history
What are the typical joints affected by gout?
- Metatarso-phalangeal joint of big toe
- Wrists
- Base of thumb
- Gout can also affects big joints like the knee and ankle
How is gout diagnosed?
Gout is diagnosed clinically or by aspiration of fluid from the joint. Excluding septic arthritis is essential as this is a potentially joint and life threatening diagnosis.
In gout, aspirated fluid will show:
- No bacterial growth
- Monosodium urate crystals
- Needle shaped crystals
- Negative birefringent of polarised light
In gout, a joint X-ray will show:
- Typically the space between the joint is maintained
- Lytic lesions in the bone
- Punched out erosions
- Erosions can have sclerotic boarders with overhanging edges
Management of acute flare of gout
- NSAIDs (e.g. ibuprofen) are first line
- Colchicine second line
- Steroids can be considered third line
For whom should colchicine be used in gout and what is a common side effect?
Colchicine is used in patients that are inappropriate for NSAIDs, such as those with renal impairment or significant heart disease.
A notable side effect is gastrointestinal upset. Diarrhoea is a very common side effect. This is dose dependent meaning lower doses cause less upset than higher doses.
Prophylaxis for gout
- Allopurinol is an xanthine oxidase inhibitor use for the prophylaxis of gout. It reduces uric acid level
- Lifestyle changes can reduce the risk of developing gout. This involves:
- losing weight
- staying hydrated
- minimising the consumption of alcohol and purine-based food (such as meat and seafood)
When should allopurinol be initiated?
Do not initiate allopurinol prophylaxis until after the acute attack is settled.
Once treatment of allopurinol has been started then it can be continued during an acute attack.
What is pseudogout?
Pseudogout is a crystal arthropathy caused by calcium pyrophosphate crystals which are deposited in the joint causing joint problems.
What is the typical presentation of pseudogout?
A typically presentation of pseudogout is an older adult with a hot, swollen, stiff, painful knee. Other joints that are commonly affected are the shoulders, wrists and hips.
It can be a chronic condition and affect multiple joints. It can also be asymptomatic and picked up incidentally on an xray of the joint.
How is pseudogout diagnosed?
Joint aspiration
