Crystal Arthropathies Flashcards
What causes gout?
Deposition of urate crystals within a joint due to high serum uric acid levels (hyperuricaemia)
How is uric acid formed?
Final compound in the breakdown of purines in DNA metabolism (adenine and guanine)
What can cause hyperuricaemia?
Renal under-excretion (exacerbated by diuretics or renal failure)
Excessive intake of alcohol, red meat and seafood
Genetic predisposition
Why do uric acid crystals precipitate in joints?
Triggered by dehydration, trauma or surgery
What is podagra?
Affected first MTP joint- classic site of involvement
What are the other common involvement sites (aside from MTP)?
Knee and ankle
How does gout present?
Intensely painful, red, hot, swollen joint- may mimic a septic arthritis
How long does an episode of gout last?
Symptoms usually last 7-10 days if untreated then resolve
What is gouty tophi?
Painless white accumulations of uric acid which can occur in soft tissue and can erupt through the skin
What can chronic gout result in?
Destructive erosive arthritis
How can you make a definitive diagnosis of gout?
Analyse a sample of synovial fluid with polarised microscopy
Uric acid crystals are needle shaped and display negative bifringence (change from yellow to blue when lined across the direction of polarisation)
How can an acute attack of gout be managed?
NSAIDs
Corticosteroids
Opioid analgesics
Colchicine (if cannot tolerate NSAIDs)
What can be used in sufferers of recurrent attacks, joint destruction or tophi?
Allopurinol or other rate lowering therapies
- should not be started until an acute attack as settled or can cause another potential flare!
What is pseudogout?
Crystal arthropathy causing acute arthritis but, caused by calcium pyrophosphate crystals
What is chondrocalcinosis?
Term describing when calcium pyrophosphate deposition occurs in cartilage and other soft tissues in the absence of acute inflammation
