Gout

Question 1

What crystals cause pseudogout and how do they appear in joint aspirate under microscopy?

Answer 1

Calcium pyrophosphate
- positively birefringent
- rhomboidal
“brick-shaped”

Question 2

What do tissues with amyloid deposits show under microscopy of joint aspirate, and what are they stained with?

Answer 2

Apple-green birefringence under polarised light

- stained with Congo Red

Question 3

How does gout appear under microscopy of joint aspirate?

Answer 3

Negative birefringent crystals

- appear needle or spindle-shaped

Question 4

What causes gout?

Answer 4

Deposition of uric acid crystals in the joint

Question 5

Risk factors for gout?

Answer 5

Age
Obesity
Male
Hypertension
Heart disease
Diabetes
Cytotoxic drugs
Diuretic use

Question 6

What can acute episodes of gout be precipitated by?

Answer 6

Trauma
Illness
Stress
Thiazide diuretics

Question 7

How does acute gout usually present?

Answer 7

Sudden pain
Swelling
Redness
- all in the first metatarsophalangeal joint (most common) or in the knee (25%)

Question 8

How is gout diagnosed?

Answer 8

Joint aspiration

- negative birefringent needle-shaped crystals on microscopy

Question 9

Treatment and prophylaxis of gout?

Answer 9

Acute attacks - NSAIDs

Prophylaxis - allopurinol

Question 10

Considerations for allopurinol use and replacement drug if patient allergic?

Answer 10

• Should not be offered to patients with recurrent/chronic gout, or who are using cytotoxic therapy
• Should not be prescribed within 1 month of an acute attack as it may precipitate a further attack
• If patient is allergic, use probenecid instead

Question 11

What are 2 other forms of gout and pathophysiology?

Answer 11

Chronic tophaceous gout - accumulation of urate in the cartilage, often in the ear and Achilles tendon

Gout nephropathy - urate deposition in the kidneys resulting in acute kidney failure and the formation of urate stones