Gout Flashcards
What are the two main types of crystal arthritis?
- Sodium urate
2. Calcium pyrophosphate
What is gout?
Gout is an auto-inflammatory arthritis associated with hyperuricaemia and intra-articular sodium urate crystals
Who does gout affect?
Men > women [5:1]
Very rare in pre-menopausal women
Very rare in young people
What are the risk factors for gout?
Rich purine foods i.e. red meat, fish
High saturated fat
Fructose containing drinks
Alcohol misuse
Increasing co-morbidity which promote hyperuricaemia
90% of gout is idiopathic.
Causes of gout can be broadly divided into 3 causes:
i. Impaired excretion of uric acid
ii. Increased production of uric acid
iii. Increased turnover of purines
What are the risk factors for impaired excretion of uric acid?
Impaired excretion of uric acid:
=> Elderly
=> Men
=> Post-menopausal women
=> Impaired renal function
=> Drugs i.e. thiazide diuretics, low-dose aspirin
=> Hypertension
=> Lead toxicity
=> Increased lactic acid production from alcohol, exercise, starvation
=> Glucose-6-phosphatase deficiency (interferes with renal excretion)
90% of gout is idiopathic.
Causes of gout can be broadly divided into 3 causes:
i. Impaired excretion of uric acid
ii. Increased production of uric acid
iii. Increased turnover of purines
What are the risk factors for production of uric acid?
Increased urate production:
=> Dietary (alcohol, sweetners, red meat, seafood)
=> Drugs i.e. warfarin, cytotoxics
90% of gout is idiopathic.
Causes of gout can be broadly divided into 3 causes:
i. Impaired excretion of uric acid
ii. Increased production of uric acid
iii. Increased turnover of purines
What are the risk factors for increased turnover of purines?
Increased turnover of purines (thus increased urate):
=> Myeloproliferative disorders i.e. polycythaemia vera
=> Lymphoproliferative disorders i.e. leukaemias
=> Others i.e. carcinoma, severe psoriasis
What are the characteristics of gout?
Acute monoarthropathy with severe joint inflammation.
> 50% occur in metatarsophalangeal joint of the big toe (podagra)
Other common joints affects = ankle, foot, small joints of hand, wrist, elbow or knee
Can be polyarticular
Assoc. with raised plasma urate
What may precipitate attacks of gout?
Trauma
Surgery
Starvation
Infection
Diuretics
What is the result of long term urate deposits?
Long term urate deposit
=> tophi in pinna, tendons and joints
=> renal disease i.e. renal stones and interstitial nephritis
What are the differential diagnosis for gout?
Septic arthritis (exclude in any monoarthropathy)
Reactive arthritis
Haemathrosis
Calcium pyrophosphate deposition (CPPD)
What are the 4 clinical stages of hyperuricaemia?
- Acute gout
=> followed by asymptomatic inter-critical phase ± a second acute attack within 2 years - Chronic interval gout:
=> acute gout attacks superimposed on low-grade inflammation and potential joint damage - Chronic polyarticular tophaceous gout (rare)
=> chronic joint pain, activity limitation, structure joint damage, frequent flares - Urate renal stone
How does acute gout present?
What are the precipitating factors for acute attack?
Middle aged man with sudden onset of agonising pain, swelling and redness of the 1st metatarsophalangeal joint (great toe).
Attack precipitated by purine rich food, alcohol excess, dehydration, diuretic therapy
Recovery assoc. with desquamation of overlying skin
25% of attacks have an additional joint affected other than great toe
What are the investigations for gout?
- Polarised light microscopy of synovial fluid
=> negatively birefringent urate crystals - Serum urate raised
(but can be normal)
How do you manage gout?
High dose NSAID - rapidly reduces pain and swelling e.g.
Naproxen 750mg
Diclofenac 75-100mg
Colchicine - if NSAIDs contraindicated - effective but slower
Corticosteroids - use in renal failure as NSAIDs + colchicine contraindicated
Rest & elevate joint
Ice packs
