crystal arthropathies Flashcards
what are crystal arthropathis
deposition of mineralised material within joints and peri-articular tissue
what causes gout
monosodium urate
what causes pseudogout
calcium pyrophosphate dehydrate (CPPD)
where does our uric acid come from
2/3 from degradation of purines
1/3 dietary
what happens to uric acid produced
majority excreted via kidney
remainder eliminated into biliary tract and converted by colonic bacterial uricase to allntoin
in majority of people with gout, hyperuricaemia results from…
reduced efficiency of renal urate clearance
overproduction causes of hyperuricemia
malignancy e.g. lymphoproliferative
severe exfoliative psoriasis
drugs e.g. ethanol, cytotoxic
HGPRT deficieny
underexretion causes of hyperuricemia
renal impairment hypertension hypothyroidism drugs e.g. low dose aspirin, cylosporin, diuretics exercise, starvation, dehydration lead poisoning
lesch Nyan syndrome
HGPRT deficiency
x-linked recessive
intellectual disability aggressive + impulsive behaviour self-mutilation gout renal disease
what is HGPRT and why is deficiency bad
enzyme involved in recycling of purine bases
when deficient, cannot salvage proteins and they are broken down and excreted as uric acid
to compensate for loss of purine bases the body produces more purines which will cause more uric acdi
pt Hx with gout
dehydration alcohol overweight classically occurs 1st MTP jiont foot pain typical episode 5-7days
gout examination
erythema of skin
podigra is sevre
tophi (accumulation of uric acid)
gout investigation
joint aspiration
management of gout: acute flare
NSAIDs
colchicine
steroids (IA, IM, oral)
management of gout: long term
if 2nd attack within 1yr
lower uric acid
drugs for lowering uric acid
xanthine oxidase inhibitor e.g. allopurinol
febuxostat
uricosuric agents
rules for lowering uric acid
- wait until acute attack has settles
- use prophylactic NSAIDs/low dose colchicine/steroids until urate level normal
- adjust allopurinol dose according to renal function
pseudogout
knee
erratic flares
pseudogout triggers
trauma
intercurrent illness
management of pseudogout
IA steroids
analgesia
NSAIDs
(no prophylactic therapies)
polymyalgia rheumatica
sudden onset of shoulder +/- pelvic girdle stiffness
polymyalgia rheumatica cycle
PMR - giant cell arthritis - high ESR anaemia - PMR
clinical features polymyalgia rheumatica
raised ESR anaemia malaise weight loss fever depression occasional arthralgia/synovitis
diagnosis of polymyalgia rheumatica
compatible Hx
age >50
ESR >50
dramatic steroid response
(no specific diagnostic test)
treatment of polymyalgia rheumatica
prednisolone 15mg per day
bone prophylaxis
gout crystals
shard shaped, negative bifringence
pseudogout crystals
rhomboid, positive bifringence
gout Rx
acute: NSAIDs, colchicine
long-term: allopurinol
gout risks
men DM, renal disease alcohol drugs: thiazide, loop diuretics, low dose aspirin HGRPT def
