crystal arthropathies Flashcards
2 main conditions
gout and psuedogout
gout is deposition of
monosodium urate
psuedogout is deposition of
calcium pyrophosphate deposition disease (CPPD)
definition of gout
type of inflammatory arthritis which is caused by the deposition of rate crystal in joints due to high serum uric acid levels (hyperuricaemia)
gout in men
is the most common type of inflammatory arthritis
what is uric acid
uric acid is the final product in the breakdown of purines in DNA metabolism
uric acid pathway
ADENOSINE> HYPOXATNHINE> XANTHINE> URIC ACID which is exerted by kidneys and GI tract or converted to allantoin
what converts hypoxanthine to xanthine
xanthine oxidase (ALLOPURINOL IS A XANTHINE OXIDASE INHIBITOR)
causes of hyperuricaemia
- decreased renal clearance due to renal failure, dehydration, thiazide diuretics (bendroflumethiazide)
- increased purines in the diet (anchovies, shell fish, red meat)
- any condition which increases cell turnover (psoriasis, sepsis, chemotherapy)
definition of hyperuricaemia
serum uric acid level greater than 7mg/dl (serum urate greater than 360)
what can the diagnosis of gout not be based upon alone
hyperuricaemia as many people do have hyperuricaema but do not develop gout
diagnosis of gout
joint aspirate and examination of aspirate using polarised light microscopy
what crystals are seen in gout
negatively birefringement needle shaped crystals
when might serum urate actually surprisingly be normal
in 25% of acute attacks of gout it will be normal because the rate is sequestered in the joint
when is the best time to measure serum urate
2 weeks after acute attack
presentation of gout
- red, hot swollen joint
- excruciating pain which often comes on over night
what is the most common joint affected in gout
1st metatarsophalyngeal joint where it is called PODAGRA
chronic gout can cause
tophi, renal stones and and an interstitial nephritis
tophi
deposit of uric acid crystals in long standing gout which is white and painless but destroys and erodes the joint
investigations
- joint aspirate
- serum urate
- raised inflammatory markers: ESR, CRP and PV
- x-ray: normal in acute attacks but in chronic gout shows erosion and joint destruction
management of acute attack of gout
- NSAIDS and co-codamol/ tramadol and ice
if NSAIDS are contra-indicated what do you use
Colchicine (too much colchicine gives you diarrhoea)
when might NSAIDS and colchicine be contra-indicated and if so what should you use instead
renal impairment so use intra-articular steroids
preventing gout
if someone has had 2 attacks within 6 months give allopurinol
