Crystal Arthropathies Flashcards
(44 cards)
1
Q
What is gout?
A
- common disorder or uric acid metabolism
- sudden onset of acute flares
- often in 1st metatarsal pharyngeal joint
- more common in men as higher uric acid levels
- peak age is 40-60 for men, 60-80 for women post menopause
- uric acid levels elevated 20 years before onset
2
Q
What happens if gout is untreated?
A
- joint destruction
- renal damage
- after first attack there is variable length of time before next attack if untreated
- second attack longer and more painful
- time between attacks will get shorter and become more severe = eventually chronic
3
Q
What is the basic pathophysiology of gout?
A
- monosodium urate crystals get deposited in small joints
4
Q
How is it a mostly inert disease?
A
- urinate crystals in synovial fluid not enough to causy flares
- crystals normally coated with serum proteins which make them inert (apolipoprotein E/B)
5
Q
How is it an acute disease?
A
- when large increase in uric acid
- bone serum proteins don’t have enough time to coat crystals
6
Q
What happens when there are uncoated crystals present?
A
- crystals embedded in synovium cause an immune response
- neutrophils enter joint and phagocytose crystals
- crystals sharp so neutrophils break
- release lysosomes, cytokines, IL1 and 8
- further inflammatory reaction = pain
- lowering pH by releasing contents so more crystals form
- repeats cycle
7
Q
In what joints does it occur more in?
A
- distal as less blood supply
- colder and lower pH
- can often spread to larger joints but rare
8
Q
What is podagra?
A
- inflammation of 1st MTP joint
9
Q
What can it lead to?
A
- renal damage
- bursitis
10
Q
What are the features of the joints?
A
- hot
- red
- exquisitely tender
- pain starts acutely, usually at night
- initially presents as polyarticular arthritis
11
Q
What is the significance of intermittent cycles?
A
- some will have attack again
- untreated 1st attacks resolve spontaneously in less than 2 weeks
- lifestyle factor important
12
Q
What are the features of untreated attacks?
A
- become polyarticular
- more proximal and upper extremity joints involved
- attacks more frequent and last longer
- chronic polyarticular arthritis almost symmetrical
- can affect other synovial structures
13
Q
What are ratphytes?
A
can get erosions outside joint surface (where tendons insert)
14
Q
What is tophi?
A
- urate crystals in soft tissues
- in 50% of untreated gout cases
- after 10 years develop
15
Q
What is the histology of gout?
A
- giant cell reaction to deposited crystals
- tissue macrophage (histocytes) form outer barrier surrounded by lymphocytes
16
Q
What is uric acid?
A
- end stage by product of purine metabolism from DNA and RNA from diet
- mainly in meat, high protein foods = beer/pork/lamb/seafood/beer
- removed by renal excretion and faeces
17
Q
What is hyperuricemia?
A
- when excretion is insufficient to maintain serum urate levels below saturation
- 6.8ml/dL
- due to renal insufficiency, dehydration, diuretics
- rarely related to overproduction of uric acid
18
Q
What are some risk factors?
A
- male
- age
- obesity
- ethnicity (pacific islanders)
- polymorphisms (genetics)
- kidney disease
19
Q
What causes elevated purine source?
A
- catabolism of purines
- tumor lysis syndrome
- diet
20
Q
What are some hyperuricemia related risks?
A
- joint inflammation
- kidney or bladder stones
- nephropathy
- CV disease
- metabolic syndrome
21
Q
What are some causes of decreased renal clearance?
A
- drugs (aspirin)
- fructose
- genetic factors
- kidney disease
22
Q
What is the gout criteria for diagnosis?
A
11 or more variables:
- more than 1 attack of acute arthritis
- max inflammation developed within 1 day
- monoarthritis attack
- redness observed over joints
- first MTP joint painful/swollen
- tophus
- hyperuricemia
> or equal to 6/11 = probably gout
4<8 = uncertain, synovial fluid analysis need
<4 = not gout
23
Q
What are the differential diagnoses?
A
- RA
- pseudogout
- septic arthritis
- reactive arthritis
24
Q
What is the synovial fluid like in gout?
A
- inflammatory
- WBC count greater than 2000/ul
- predominance of polymorphonuclear neutrophils
25
Why is elevated serum uric acid not diagnostic?
- people have it without gout
| - only 5-20% of those with gout have it
26
What are the imaging methods?
- x-ray
- ultrasound
- DEXA
27
What would an x-ray show?
- maintenance of joint space
- erosion outside joint capsule
- erosion with overhanging edges
28
What would an US show?
- soft tissue swelling
| - Doppler = increased blood flow to that joint
29
What would a DEXA show?
- detect uric acid crystal deposits in all late stage gout
- detect a lot with early stage too
- measure monosodium urate volume and changes following treatment
- predict gout flare
30
How would there be joint damage?
- tophaceous deposits= bone erosions
- MSU crystals surrounded by granulomatous tissue reaction
- produce pro-inflammatory cytokines (IL1,6 TNFa)
- stimulate osteoclasts
31
What are the acute treatment methods?
- NSAIDs
- colchicine
- corticosteroids
- IL1 biologicals
32
How should NSAIDs be used?
- start with highest dose for 2-3 days
- taper down over 2 weeks
- gout symptoms should be absent for 2 days before treatment stopped
33
Why are colchicine second line?
- narrow therapeutic window
| - risk of toxicity
34
Who are corticosteroids used for?
- those who cannot use NSAID or colchicine
35
What biologicals should be used?
- riloncept
- canakinumab
- anakinra
- reduce length of attack and reoccurrences
- for patients who have severe/frequent flares
36
What are the long term treatment methods?
- allopurinol
- probenecid
- rasburicase
37
What is allopurinol?
- blocks xanthine oxidase
- reduces generation of uric acid
- alternative is febuxostat
38
What is probenecid?
- uricosuric
- increases uric acid excretion
- fewer significant adverse effects
39
What is rasburicase?
- catalyses conversion of acid allantoin
40
What is pseudogout?
- other crystal arthroplasty
- calcium pyrophosphate deposition disease (CPDD)
- metabolic arthropathy associated with OA
- chondrocalcinosis
- acute deposition of crystal in and around joints
- majority of patients asymptomatic
41
What are the features of pseudogout?
- half of those over 85 have evidence of chondrocalcinosis
- pseudo OA with osteophytes and soft tissue calcifications
- asymptomatic where only radiographic findings
- normally crystals do not interfere with joint
- acute = triggered by trauma/reduction of serum calcium = release of calcium in joint, stimulates osteoclasts
- knee commonly affected
42
How is pseudogout diagnosed?
- synovial fluid analysis
| - US
43
What is synovial fluid like is pseudogout?
- mild to moderate inflammation
| - rhomboid shaped weak birefringent crystals
44
What does an US show in pseudogout?
- calcification within soft tissue and articular cartilage
- chrondocalcinosis of articular disc/atypical OA of hands
- OA in same/neighbouring joints
