Crystalline Arthropathies Flashcards
what is hyperuricemia?
serum urate values >6.8 mg/dl
what is gout?
inflammatory arthritis developing as a consequence of urate deposition in the joint
where does most acute gouty arthritis occur?
1st MTP (podagra)- (90% )
what is the order of freuqnecy of joints involved?
- 1st MTP
- mid-foot
- ankle
- heel
- knee
- wrist
7;. finger - elbow
what are the 4 stages of gout?
- asymptomatic hyperuricemia
- acute flares
- intercritical segments
- advanced gout
what is asymptomatic hyperuricemia?
elevated serum urate with no clinical manifestations of gout
what happens in acute flares stage of gout?
acute inflammation in the joint caused by urate crystallization
what happens in intercritical segments?
the intervals btwn acute flares
what happens in advanced gout?
long-term gouty complications of uncontroleld hyperuricemia
what are some pathognomonmic changes of gouty tophus on radiograph?
“overhanging edges” with periarticular erosions
why is gout on the rise?
- increased longevity
- aging population
- increased comorbidity
- low dose aspirin
- thiazides
- fructose intake
which degradation pathway produces uric acid?
purine degradation
which enzyme is targeted for treatment of gout because it catalyzes the final conversion to uric acid?
xanthine oxidase
at what level does urate crystallize?
at a level of 6.8 mg/dL
which medications are risk factors for development of gout?
- diuretics- lead to increased uric acid reabsorption
2, low dose aspirin- increased serum urate and decreased uric acid clearance - pyrazinamide, ethambutol, niacin- gout observed at higher incidence
which patient population is at risk for development of gout?
transplant patients
bc they are often on calcineurin inhibitors that put them at risk for hyperuricemia
which drug is a contrindication to allopurinol use?
azathioprine
*bc it needs xanthine oxidase, which allopurinol blocks
people who have gout often have what other disease?
obesity metabolic syndrome Diabetes mellitus heart failure hyperlipidemia hypertension
what is the gold standard for diagnosing gout?
synovial fluid analysis- visualizing MSU crystals
how would you describe gout crystals?
negatively birefringent under polarized light
what acute changes are seen in gout radiographs?
acutely, often only soft tissue swelling is seen
what chronic changes are seen in gout radiographs?
- “overhanging edges”
- erosions w/ demarcated round deficits with sclerotic margins
- very destructive
how do you terminate acute flare?
- control crystal-induced inflammation and pain using NSAIDs, colchicine, steroids
what are the critical considerations for terminating the acute flare?
- rapid initiation of therapy
- appropriate duration of therapy
which drug to treat gout-inflammation is contraindicated in dialysis patients?
colchicine
which drug should not be given thru IV?
colchicine
what is the first-line treatment for gout?
intraarticular corticosteroids
what are 2 approved urate-lowering agents for gout?
uricosuric agents
xanthine oxidase inhibitor (allopurinol & febuxostat)
what are the limitations of uricosuric agents like probenecid?
- efficacy dependent on functioning kidneys (Crcl>50 mL/min)
- 2x a day dosing
- risk of UA crystallization, stone formation
what are the advantages of xanthine oxidase inhibitors?
- single daily dose
- efficacious in patients w/ renal insufficiency
- effective for both overproducers and underexcretors
what is the #1 side effect of allopurinol?
ironically, it is gout flares.
lowering serum urate mobilizes deposited crystals
what are the drug interactions with allopurinol?
azathioprine
6-mercaptopurine
what is the 2nd most common side effect of allopurinol?
severe hypersensitivity syndrome (a rash that occurs early on in treatment)
what are prophylactic treatments for gout flares?
NSAIDs, colchicine
*initiate agents prior to starting urate-lowering therapy
what is the formation of CPPD crystals in articular hyaline and fibrocartilage called?
CPPD deposition disease
what is the CPPD -crystals induced inflammation called?
pseudogout
what is severe, atypically distributed structural joint damage called?
pyrophosphate arthropathy
what is pathologically or radiologically evident cartilage calcification called?
chondrocalcinosis
what age population gets pseudogouts?
elderly , 80-90 y/o
which metabolic disease is associated with CPPD?
hemachromatosis
what is the order of likelihood that psuedogout affects joints?
knees
wrists
shoulders
ankles
describe the cryastals in pseudogout
blue (+) birefringent crystals
describe treatment for CPPD.
no mechanis, to reduce CPPD crystal load so is more frustrating to treat
