Crystal arthropathies Flashcards
What is gout?
A crystal arthropathy caused by deposition of uric acid crystals within a joint
What is uric acid?
The final breakdown compound of purines in DNA metabolism
What are some of the causes of hyperuricaemia?
Underexcretion - exacerbated by diuretics or renal failure
Ingestion of too much alcohol, sea food and red meat
What might trigger the formation of uric acid crystals in joints?
Dehydration
Surgery
Trauma
Chemotherapy agents
Which sights are most commonly affected by gout?
First metatarsal (big toe, known as Podagra)
Knee
Ankle
How does gout present?
Hot, red, swollen joint
Unilateral
What other pathology can gout be similar to?
Septic arthritis
What are gouty tophi?
Painless white collections of uric acid which can occur in the soft tissues and erupt through the skin
What can chronic gout result in?
Destructive erosive arthritis
How can gout be diagnosed?
Aspiration of fluid in joint
Synovial fluid examined under polarised microscopy to view uric acid crystals
C&S of fluid done to rule out infection
What do the uric acid crystals of gout look like under polarised microscopy?
Needle shaped
Display negative birefringence (change from yellow to blue when lined across direction of polarisation)
What is pseudogout?
A crystal arthropathy caused by calcium phosphate crystals collecting in joints
What does chondrocalcinosis mean?
The occurrence of deposition of calcium phosphate crystals in cartilidge and soft tissue in the absence of acute inflammation
Which joints tend to be affected by pseudogout?
Knee
Wrist
Ankle
What conditions can pseudogout co-exist with?
Hyperparathyroidism Hypothyroidism Renal osteodystrophy Haemachromotosis Wilson's disease
