Gout & Pseudogout Flashcards
What is gout?
Hyperuricaemia and deposition of monosodium urate crystals causing attacks of acute inflammatory arthritis, gouti tophi, urate nephropathy and uric acid nephrolithiasis.
Discuss the pathophysiology of gout
- Uric acid exists as urate at physiological pH
- High levels of urate causes super-saturation and crystal formation
- Monsodium urate cystals deposit in joint and cause inflammatory response
What crystals are deposited in joints in gout?
Monosodium urate crystals
State some risk factors for gout
- Age >40yrs
- Male
- Obesity
- High purine diet (e.g. meat, seafood)
- Alcohol (especially beer)
- Diuretics
- Existing cardiovascular disease (e.g. dyslipidaemia, coronary artery disease, CHF)
- Existing kidney disease
- Family history
- Diabetes
- Smoking
- High fructose intake
State some symptoms of gout
- Joint pain
- Joint swelling
- Joint stiffness (which is worse after rest)
- Hot joint
- Joint tenderness
Typically presents with a single acute, hot, swollen and painful joint (it can affect more than one joint)
What might you find on clinical examination of someone with gout?
Joint is:
- Swollen
- Hot
- Tender
- Gouty tophi
What is gouty tophi?
Gouty tophi are subcutaneous deposits of urica acid typically affecting small joints and connective tissue of hands, elbows and ears. DIP are most affected in hands
Which joints are typically affected by gout?
- Metatarsophalangeal joint of great toe
- Wrists
- Carpometacarpal joint of first digit (thumb)
- Also affect large joints e.g. knee & ankle
Which joint is commonly involved in the first presentation of gout?
1st metatarsophalangeal joint
(podagra)
What is podagra?
Gout affecting the foot, typically the 1st metarsophalangeal joint
What are your differentials for someone presenting with gout-like symptoms?
Which one MUST you rule out
- Septic arthritis *MUST RULE OUT
- Pseudogout
What investigations would you do if you suspect gout, inlcude:
- Bedside
- Bloods
- Imaging
*Where appropriate, justify each
Bedside
- Arthrocentesis
Bloods
- FBC: rasied WCC in infection
- U&Es: urate nephropathy
- CRP: inflammation
- Uric acid level
Imaging
- X-ray of joint
Describe what the aspirated fluid will most likely look like if a pt has septic arthritis
- Septic arthritis: purulent
- Gout: cloudy
When you send aspirated fluid to the lab, what will it show if the pt has gout?
- No bacterial growth
- Needle shaped crystals
- Negative birefringement of polarised light
- Monsodium urate cyrstals
What might you see on x-ray of pt with gout?
- Typically joint space is maintained
- Lytic lesions in bone
- Punched out erosions
- Punched out erosions can have sclerotic borders with overhanding edges
Discuss the management of gout, include:
- Conservative management
- Pharmacological management
Conservative
- Weight loss
- Regular exercise
- Staying hydrated
- Minimising alcohol & purine based foods (e.g. meat & seafood)
- Smoking cessation
Pharmacological management
- Acute flare:
- First line= NSAIDs
- Second line= colchicine
- Third line= steroids
- Chronic cases:
-
Urate lowering therapy
- 1st= alopurinol
- 2nd= febuxostat
- 3rd= benzbromarone & sulfinpyrazone
-
Urate lowering therapy
*BUT REMEMBER: if septic athritis is differential start Abx ASAP don’‘t wait for aspiration results
State what class of drug allopurinol and febuxostat belong to
Describe the mechanism of action
- Xanthine oxidase inhibitors
- Reduce urate formation
Describe the mechanism of action of benzbromarone & sulfinpyrazone
Increase renal excretion of uric acid
(Have more side effects compred to xanthine oxidase inhibitors therefore used less commonly)
Which pts may NSAIDs not be appropriate for and therefore what is the next line therapy in acute gout attack?
Inappropriate for:
- Asthmatic
- Renal impairment
- Significant heart disease
- IBD
Give cholchicine instead.
What is a notable ADR of cholchicine?
GI upset e.g. diarrhoea
Discuss any ‘rules’ regarding initiating allopurinol
Do not initiate allopurinol prophylaxis until after acute attack has settled because allopurinol initially causes uric acid level to increase.
However, once treatment of allopurinol has been started it can be continued in an acute attack as it only increases uric acid initially when first started
State some potential complications of gout
- Uric acid nephropathy
- Uric acid nephrolithiasis
- High risk of cardiovascular disease
Asymptomatic hyperuricaemia requires treatment; true or false?
False
Discuss the prognosis of gout
- Pts usually get 2nd flare within 1 or 2 yrs of first attack
What is psuedogout?
Inflammatory arthritis caused by calcium pyrophosphate crystal deposition joints (crystal arthropathy)
Discus the pathophysiology of pseudogout
- Caclium pyrophosphate crystals can be shed from cartilage into articular space
- Crystals induce inflammatory response
State some risk factors for pseudogout
- Age
- Family history
- Previous injury or surgery to joints
- Metabolic disorders e.g. hyperparathyroidism, haemochromatosis
State the symptoms of pseudogout
Which joints are commonly affected?
Joint is:
- Painful
- Swollen
- Hot
It typically affects the knee however other commonly affected joints are shoulers, wrists & hips. It is chronic and can affect multiple joints
State what you might find on clinical examination of someone with psuedogout
Joint is:
- Swollen
- Painful
- Hot to touch
What investigations would you do if you suspect pseudogout, include:
- Bedside
- Bloods
- Imaging
Same as for gout. All about ruling out/distinguishing between gout, pseudogout & septic arthritis as all present similarly
Bedside
- Arthrocentesis
Bloods
- FBC: rasied WCC in infection
- U&Es: urate nephropathy
- CRP: inflammation
Imaging
- X-ray of joint
What will the aspirated fluid show in pseudogout when viewed under the micrscope?
- No bacterial growth
- Calcium pyrophosphate crystals
- Rhomboid shaped crystals
- Positive birefringement of polarised light
IMAGE ON THE RIGHT!!!!!!
What will the x-ray show of a joint with pseuodgout?
- Chondrocalcinosis: thin white line in middle of joint space caused by calcium deposition. Pathopneumonic of pseudogout
-
Changes similar to those seen in OA:
- Loss of joint space
- Osteophytes
- Subarticular sclerosis
- Subchondral bony cytes
Discuss the management of pseudogout
Symptoms usually resolve spontaneously over several weeks however managment may involve:
- NSAIDs
- Colchicine
- Joint aspiration
- Steroid injections
- Oral steroids
- Joint wash out
*NOTE: order depends on if it is mono- or poly-articular disease and whether joint is accessible for injection and whether pt responds.
*BUT REMEMBER: if septic athritis is differential start Abx ASAP don’‘t wait for aspiration results
Discuss the potential complications of pseudogout
Complications are generally related to treatment e.g:
- Bleeding & bruising around injection site of intra-articular injection
