Gout

1
Gout
2
Cause

• Urate crystal deposits due to disorder of purine
  metabolism
• Purine gt breakdown byproduct of uric acid gt2/3
  excreted via kidney 1/3 via gut
• Higher risk of crystallisation with a higher uric
  acid level and lower temp

3
Uric acid

• product of the breakdown of DNA from body cells
  and food.
• The more nucleoprotein there is in food, the
  larger the quantity of DNA.
• A low purine diet is occasionally used in
  patients suffering from gout. The principle
  sources of purines are
• fish - anchovies, crab, fish roes, herrings,
  mackerel, sardines, shrimps, sprats, and
  whitebait
• meat - liver, heart, kidney, and sweetbreads
• meat extracts - OXO, Bovril, Broth, stock
• In general, vegetables contain relatively low
  levels of DNA,
• although asparagus and pulses are above average.

4
Alcohol and Gout

• alcohol metabolism to lactate contributes to
  urate retention?
• port, some red wines and stouts contain purines
  or oxypurines, which lead to an increased purine
  load?
• alcohol may contribute to obesity which is
  associated with under excretion of uric acid
• Patients with a history of gout are advised to
  drink
• plenty of fluid, approximately 2 litres per day
  (non
• alcoholic).

5
Pathology

• Monosodium urate crystals are deposited in and
  around joint in synovial fluids
• Tophus may form in bursae, tendons cartilage or
  periarticular bone
• 2ry damage gt Degenerative arthritis
• Crystals in renal parynchyma may cause renal
  failure
• in urine gt urate calculi
• Immunological acceleration ?preciptitation

6
Acute gout

• Sudden onset
• Lasts 1-2w
• May be triggered - trauma operation alcohol
  exercise
• Sites
• 1st MTP (75)
• Ankle
• Finger
• Olecranon

7
Signs

• Swollen hot tender joint
• Overlying red shiny skin
• May have fever nausea mood swings

8
Differential diagnosis

• infection
• cellulitis
• septic bursitis
• aseptic arthritis
• Gonococcal arthritis
• rheumatoid arthritis
• polyarticular gout that affects the fingers may
  be mistaken for rheumatoid arthritis?if there are
  elbow tophi these may be mistaken for rheumatoid
  nodules
• Bunion
• chondrocalcinosis - pseudogout
• seronegative arthritis
• Trauma
• Haemophilia

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Chronic gout

• A polyarticular gout
• tophi may form around joints and often also in
  the pinna of the ear and with time may ulcerate
  and discharge
• may cause joint stiffness and deformity as a
  result of joint erosion
• may cause renal damage due to deposition of urate
  crystals in the renal parenchyma
• urate urolithiasis occurs in 10 rarely chronic
  urate nephropathy with renal failure may develop

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Acute on chronic gout
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Investigation

• Uric acid level
• Aspirate of synovial fluid in polarised light -
  neg bifringent crystal
• XR
• Leucocytosis ESR CRP

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Gout XR

• Acute - may show soft tissue swelling
• Chronic
• Narrowed joint space
• Secondary osteoarthritis
• Periarticular excavations
• Osteoporosis

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• Increased soft tissue density and volume with
  increased joint space
• Bony erosions rimmed by sclerotic bone
• Classic C shaped rat bite erosion Martels sign
  with overhanging edge
• Eventually irregular regular joint space
  narrowing due to cartilage destruction and
  associated degenerative arthritis. In
  longstanding cases there may be tophi deposits (a
  caseous cheese like substance) leading to
  further erosion of bone.

14
Treatment of acute attack

• Limit exacerbating factors
• Medication - diuretics aspirin
• Reduce alcohol
• Reduce purine rich foods
• Avoid starting allopurinol/ uricosurics
  (exacerbate and prolong an attack indefinately)

15
Treatment of chronic gout

• Allopurinol - xanthine oxidase inhibiter reduces
  synthesis of uric acid
• Probenecid sufinpyraxone (uricosuric) increase
  urinary excretion of uric acid
• Starting treatment
• Not during acute attack
• Prophylactic nsaid or colchicine for at least 1st
  3 months
• If an acute attack starts during prophylaxis
  continue it while treating acute attack

16
Raised uric acid

• risk of gout not inevitable"..hyperuricaemia,
  in the absence of gout, does not require
  treatment unless it is accompanied by other,
  extra-arthritic, complications such as uric acid
  nephropathy or urolithiasis.."
• Associated with hyperlipidemia, dehydration
  hypertension
• Risk factors
• cell turnover (eg lymphoma)
• Reduced excretion
• High protien diet
• Drug induced
• Diuretic (occurs in 30 of hypertensives on this
  treatment) stop treatment if gout develops or
  avoid initiation if h/o gout

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Gout or pseudogout?

• Pseudogout
• Elderly
• Large joints esp knee
• Mod pain and swelling
• XR calcification articular cartilage menisci
• Calcium pyrophosphate positively bifringent
• Rest nsaid joint aspiration

• Gout
• gt40
• small joints esp 1st MTP
• Severe joint pain swelling
• XR soft tissue swelling
• Uric acid crystals neg bifringent
• Rest nsiad prohylaxis
• hyperuricaemia

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Pseudogout

• Positively bifringent crystals
• Exclude assoc conditions
• Forms
• Asymptomatic
• Pseudogout
• Polyarticular
• Chronic destructive (charcots)
• Chronic arthropathy
• Polymalgic form