Crystal Arthropathies

Question 1

How is gout caused?

How does this appear under microscopy?

Answer 1

Deposition of urate crystals (monosodium urate) within a joint

Usually associated with high amounts of uricaemia (due to undersecretion or overproduction of uric acid)

Under polarised light microscopy uric acid crystals appear as needle shaped with a strong NEGATIVE birefringence

Question 2

Gout - treatment

Answer 2

Acute attacks - NSAIDs, steroids, opioid analgesics and colchicine (for patients that cannot tolerate NSAIDs)

Prevention of further attacks - allopurinol (NB - do not use this in an acute setting!!! May precipitate further attacks of gout)

Question 3

How does allopurinol work in the treatment of gout?

Answer 3

Targets Xanthine Oxidase, preventing the conversion of Xanthine into uric acid

Question 4

Accumulation of what causes Pseudogout?

How does this appear on polarised microscopy?

Answer 4

Accumulation of calcium pyrophosphate crystals

Appear as positively birefringent on polarised microscopy

Question 5

How is psuedogout treated?

Answer 5

Same as Gout (NSAIDs, steroids, opioid analgesics and colchicine if the patient cannot tolerate NSAIDs)

However, there is no use for allopurinol as the xanthine pathway is not involved