Gout (crystal arthritis) Flashcards
What is gout?
Gout (crystal arthropathy)
- Acute mono-arthropahy with severe joint inflammation
- from deposition of monosodium urate crystals
What is the presentation of gout?
Presentation:
- Sudden onset big toe pain e.g. >50% MTP of big toe
- or can be:
- foot, ankle, hand, wrist, elbow or knee e.g. distal
- 90% have monoarthritis
- In chronic gout –> Gouty tophi
- Achilles, elbow, knee, ear
What are possible ddx of gout? e.g. monoarthritis (90%)
DDx:
- Septic arthritis,
- Hemarthrosis,
- CPPD (psuedogout)
- Palindromic RA (episodic comes and goes off differing joint pain NB: usually 2 or 3 involved)
What are some triggers for gout?
Gout triggers:
Meds: diuretics, ASPIRIN
?physcial damage to body: trauma, surgery,
?immune supression: starvation, infection,
What are the caues of gout?
Causes:
- 1ry –> hereditary
- (young males, overproducers, associated with hyper-uricaeic nephropathy),
- 2ndry –>
- 90% = Under-excretion:
- renal failure,
- alcohol excess,
- diuretics
- 10% = Overproduction:
- high dietary purines (protein & red meat),
- high RBC turnover (purine breakdown -> urate) e.g. tumour lysis syndrome
- cytotoxic agents (tumour lysis),
- leukaemia,
- 90% = Under-excretion:
What are the RF/disease assocations with gout?
Associations:
- cardiovascular disease,
- HTN,
- DM,
- CKD (e.g. renal falure = under excretion, DM and HTN can affect kidneys and BV’s e.g. so can CVS)
What would you see on an X-ray of gout e.g. of the MTPJ?
- peri-articular erosions (“punched out erosions”)
- soft tissue swelling
- NB: NORMAL joint space
What Ix would be done for acute gout?
-
Aspirate -
-
polarised joint microscopy shows
-
negatively birefringent needle shaped urate crystals
- e.g. blue/yellow refraction depending on angles of microscopy
-
negatively birefringent needle shaped urate crystals
- NB: IF +ve birefringent rhomboid crystals = pseudogout
-
polarised joint microscopy shows
-
X-ray -
- soft tissue swelling and/or ‘punched-out’ erosions
What is the Rx for acute gout?
Prevention & lifestyle modifications:
- Rest
- High fluid intake
- Reduce thiazides, alcohol, red meat
Meds:
- High dose NSAIDs* (naproxen/diclofenac) or coxib
- e.g. selective Cyclooxegenase 2 inhibitors (etoricoxib 12mg.24h PO)
- –> symptoms should subsite in 3-5d
- If NSAID is CI’d –> Colchicine*
- which blocks the neutrophils to mediated inflammatory responses caused by monosodium urate crystals in synovial fluid) -
- Colchicine causes diarrhoea
- Steroids (oral, IM or intra-articular) if needed e.g. prednisolone 40mg/24h PO for 3d then taper
*Note: NSAIDS & colchicine are both problematic in renal impairment :( (coxib not though)
What investigations can be done for chronic gout?
Bloods -
- serum urate
>2wks post-attack resolution –> usually raised, may be normal
What are the cirteria for gout prophylaxis e.g. chronic gout rx?
Prophylaxis if:
Severe disease sx e.g.
- >2 attack in 1 year
- Gouty tophi
Renal stuff:
- Renal stones
- CKD with GFR <30
- On cytotoxic or diuretics
What is the prophylaxic tx of gout?
- allopurinol (xanthine oxidase inhibitor e.g. inhibs uric acid production)
- wait 2-3weeks post attack, stay on for life, cover with another medication initially (NSAID/colchicine);
- or
- febuxostat (newer xanthine oxidase inhibitor
- same method as allopurinol but less likely to get rash)
What are the SE of allopurinol?
- rash, (why febuxostat is advantageous)
- fever,
- low WCC,
- can trigger attack on introduction - hence cover w/nsaids/colchicine
How do you prevent gout?
- Weight loss
- & avoid
- prolonged fasting (as dc GFR)
- excess etoh
- purine rich meat
- remove low dose aspirin (as increases serum urate)
What is CPPD (psuedogout)?
- intra articular
- deposition of calcium pyrophosphate
- = calcium pyrophosphate deposition disease
- (is an umbrella term used to describe different patterns of disease)
