Crystal Arthropathies Flashcards
Gout is a disorder of what metabolism
Uric acid metabolism
What causes gout
Deposition of mono sodium rate crystals in soft tissues due to disordered uric acid metabolism
What triggers a gout attack
Uncoated mono sodium rate crystals or sudden large change in crystal concentration
Are monosodium irate crystals inert or active when coated with serum proteins
Inert
Cycle of gout attack
Attack starts -> crystals form -> WBC attack -> cell popped by crystals -> proteins released -> further inflammation + pain -> proteins decr pH allowing more crystals to form
Is gout usually mono or polyarticular
Monoarticular
Podagra
Gout affecting 1st MTP joint in big toe
Most common joints effected by gout
1st MTP
other small lower extremity joints
How does a gout attack begin
Suddenly
Max intensity in 8-12hrs
Are men or women affected by gout more
Men
Characteristics of gout affected joint
Red
Hot
Exquisitely tender
Pain starts acutely usually at night
Why do untreated 1st attacks resolve spontaneously in less than 2 weeks
Crystals get coated by serum proteins or phagocytosed
How does gout progress over time
Attacks get closer,more painful, and last longer
Attacks eventually become continuous
Becomes polyarticular
Can affect other synovial structures
Gouty tophi
Nodular masses of monosodium urate crystals in soft tissues
What cells surround ms urate crystals in tophi
Lymphocytes
Macrophages
Foreign body giant cells
Uric acid is an end stage by product of which metabolism
Purine metabolism
How is Uric acid removed
Urine
Faeces
What serum urate level is saturation
6.8mg/dL
What is high serum urate called
Hyperuricemia
Gout risk factors
Foods high in purines
Under excretion of Uric acid - renal insufficiency, dehydration, diuretics
How many characteristics on the gout criteria are needed for a probable gout diagnosis
6+
What is needed for a definitive gout diagnosis
Urate crystals in joint fluid during attack and joint fluid culture negative for organisms during attack
Gout synovial fluid characteristics
Inflammatory
High WBCs
Polymorphonuclear neutrophils
Urate crystals
What level of hyperuricemia requires treatment
11mg/dL+
How does gout effect joint space
No effect
Gout characteristics on XR and ultrasound
Soft tissue swelling
Incr blood flow
Erosion outside joint capsule
Rate bite erosions
What imaging type can detect and measure Uric acid crystals
Dual energy computed tomography DECT
How can tophi lead to bone erosion
Produce pro inflammatory cytokines which stimulate osteoclasts via RANKL
Acute gout attack treatment
NSAIDS
Colchicine - used less now
Corticosteroids
IL1 biologicals - rilonacept canakinumab anakinra
How long should NSAID dose be changed during and after a gout attack
High for 2-3 days
Taper over 2 wks
Keep taking until symptoms absent for 2 days
Why is colchicine used less for gout now
Narrow therapeutic window
Toxicity risk
Colchicine MOA
Blocks mitosis by preventing Tubulin polymerisation decreasing neutrophil numbers
Why is coffee mildly protective against gout
Increase urate excretion
Chronic gout treatment
Decr Uric acid level
Allopurinol
Probenecid
Rasburicase
Allopurinol MOA
Inhibits Xanthine oxidase -> decr Uric acid generation
Probenecid MOA
Incr uric acid excretion
Rasburicase MOA
catalyses conversion of uric acid to allantoin
What is calcium pyrophosphate deposition disease also known as
Pseudogout
Calcium pyrophosphate deposition disease
Acute deposition of calcium pyrophosphate crystals in and around joints due to excess Ca and PO4
Pseudogout/CPDD symptoms
Pseudo OA symptoms or asymptomatic
Pseudogout/CPDD X-ray findings
Osteophytes
Soft tissue calcification
Chondrocalcinosis
What causes joint inflammation in Pseudogout/CPPD
Release of CPDD crystals into joint space -> phagocytosis of crystals -> cytokine release -> inflammation
What triggers acute Pseudogout/CPDD attacks
Trauma
Rapid serum ca conc decr
Gout crystal shape and charge
Negative charge
Needle shape
CPDD crystal charge and shape
Positive charge
Rhomboid shape
Pseudogout/CPDD treatment’s
Intra articular corticosteroids
NSAIDs
What condition can rarely have cholesterol and lipid crystals in the synovial fluid
RA