Crystal arthropathies

Question 1

what is gout

Answer 1

a crystal arthropathy caused by deposition of urate crystals within a joint due to high serum uric acid levels (hyperuricaemia)

uric acid is the final compound in the breakdown of purines in DNA metabolism (adenine & guanine).

hyperuricaemia may be due to renal underexcretion (which can be exacerbated by diuretics or renal failure) or due to excessive intake of alcohol, red meat and seafood.

some evidence for a genetic predisposition.

Question 2

classic sight of gout

Answer 2

first (MTP) joint is the classic site of disease (known as Podagra) with the ankle and knee the other most commonly affected joints.

Question 3

symptoms gout (3)

Answer 3

an intensely painful red, hot swollen joint which may mimic a septic arthritis.

symptoms usually last for 7-10 days if untreated then resolve.

gouty tophi are painless white accumulations of uric acid which can occur in the soft tissues and occasionally erupt through the skin.

Question 4

chronic gout

Answer 4

can result in a destructive erosive arthritis

Question 5

investigation & diagnosis gout (3)

Answer 5

sample of synovial fluid with polarised microscopy

uric acid crystals are needle shaped and negative birefringence

(change from yellow to blue when lined across the direction of polarization).

Question 6

treatment acute gout attack (4)

Answer 6

NSAIDs

corticosteroids

opioid analgesics

colchicine for patients who cannot tolerate NSAIDs.

Question 7

treatment reccurent gout attack (2)

Answer 7

allopurinol or other urate lowering therapies

should not be started until an acute attack has settled as they can potentiate a further flare.

Question 8

what is pseudogout (2)

Answer 8

crystal arthropathy causing an acute arthritis

caused by calcium pyrophosphate crystals.

Question 9

chondrocalcinosis (2)

Answer 9

when calcium pyrophosphate deposition occurs in cartilage and other soft tissues in the absence of acute inflammation.

Both come under the umbrella of Calcium Pyrophosphate Deposition disease (CPPD).

Question 10

symptoms + other presentations (7)

Answer 10

knee, wrist and ankle.

exact cause is unknown

coexist with hyperparathyroidism, hypothyroidism, renal osteodystrophy, haemochromatosis and Wilson’s disease.

Question 11

treatment

Answer 11

NSAIDs

corticosteroids (systemic and intra‐articular)

occasionally colchicine

rehydration