Crystal Arthropathy (gout)

Question 1

Definition

Answer 1

A disorder of uric acid metabolism causing recurrent bouts of acute arthritis caused by
deposition of monosodium urate crystals in joints, and also soft tissues and kidneys

Question 2

Aetiology

Answer 2

• The main metabolic disturbance is hyperuricaemia
• This may be caused by:

o Increased urate intake or production
• Increased dietary intake
• Increased nucleic acid turnover (e.g. lymphoma, leukaemia, psoriasis)
• Increased synthesis of urate (e.g. Lesch-Nyhan syndrome)

o Decreased Renal Excretion
• Idiopathic
• Drugs (e.g. ciclosporin, alcohol, loop diuretics)
• Renal dysfunction

Question 3

Epidemiology

Answer 3

• 10 x more common in MALES
• Very rare pre-puberty
• Rare in pre-menopausal women
• More common in HIGHER social classes

Question 4

Precipitating factors

Answer 4

• Trauma
• Infection
• Alcohol
• Starvation
• Introduction or withdrawal of hypouricaemic agents

Question 5

Presenting symptoms and signs on physical examination (acute attack)

Answer 5

• Sudden excruciating monoarticular pain
▪ Usually affecting the metatarsophalangeal joint of the great toe (podagra)
• Symptoms peak at 24 hrs
• They resolve over 7-10 days
• Sometimes, acute attacks can present with cellulitis, polyarticular or periarticular involvement
• Attacks are often recurrent
• Patients are symptom-free between attacks

Question 6

Intercritical gout

Answer 6

DEFINITION: asymptomatic period between acute attacks

Question 7

Presenting symptoms and sign on physical examination (chronic)

Answer 7

• Chronic Tophaceous Gout
o Follow repeated acute attacks

o Symptoms:
• Persistent low-grade fever
• Polyarticular pain with painful tophi (urate deposits)
▪ Best seen on tendons and the pinna of the ear

Can also get symptoms of urate urolithiasis (renal calculi symptoms)

Question 8

Investigations

Answer 8

• Synovial Fluid Aspirate
o Monosodium urate crystals will be seen
o They are:
• Needle-shaped
• NEGATIVE birefringence under polarised light microscopy
o Microscopy and culture will also be performed to exclude septic arthritis

• Bloods
o FBC - raised WCC
o U&Es
o Raised urate
o Raised ESR

• AXR/KUB Film
o Uric acid renal stones may be seen