gout and pseudogout Flashcards
definition of gout
disorder of uric acid metabolism
= recurrent bouts of acute arthritis from deposition of monosodium urate crystals in joints and soft tissues and kidneys
definition of pseudogout
Arthritis associated with deposition of calcium pyrophosphate dihydrate(CPPD) crystals in joint cartilage.
aetiology of gout
underlying metabolic disturbance: hyperuricaemia, caused by: increased urate intake or production:
- increased dietary intake
- increased nucleic acid (purine) turnover eg lymohoma, leukaemia, polycythaemia vera, psoriasis
- increased synthesis (e.g. Lesch–Nyhan syndrome)
decreased renal excretion
- idiopathic
- drugs - (e.g. CANT LEAP: ciclosporin, alcohol, nicotinic acid, thiazides, loop diuretics, ethambutol, aspirin, pyrizinamide)
- renal dysfunction
= deposition of monosodium urate crystals in and near joints
lesch-Nyhan syndrome
from hypoxanthine–guanine phosphoribosyl transferase deficiency
presents with chorea, low IQ, self mutilation
aetiology of pseudogout
CPPD crystal formation is initiated in cartilage near the surface of chondrocytes
associated with excessive cartilage pyrophosphate production = local calcium pyrophosphate supersaturation and CPPD crystal formation/deposition.
shedding of crystals into the joint cavity precipitates acute arthritis
crystals deposit in floating cartilage
things that predispose pseudogout
most causes of joint damage - osteoarthrits, trauma
old age
haemochormatosis
hyperparathyroidism
hypomagnesaemia
hypophosphatasia
familial cases and metabolic diseases
provoking factors for pseudogout
intercurrent illness
surgery
local trauma
epidemiology of gout
prevalence 0.2%
men
middle aged
very rare in pre-puberty, and pre-menopausal women
more common in higher social class
epidemiology of pseudogout
female more
>60yrs
sx of acute gout attack
may be precipitated by trauma, infection, alcohol, starvation, introduction or withdrawal of hypouricaemic agents
sudden, excruciating monoarticular pain (monoarthropathy) - severe, tender
stiff - pain limits movement
swelling - marked erythema/soft tissue oedema
usually metatarsophalangeal joint of great toe
other joints: ankle, foot, small joints of the hand, wrist, elbow, knee
can be polyarticular
symptoms peak at 24hr, resolve in 7-10days
occasionally present as cellulitis, polyarticular or periarticular involvement
attacks are recurrent, symptom free in between
what is intercritcal gout
asymptomatic between acute attacks
what is chronic tophaceous gout
follow repeated acute attacks
persistent low grade fever
polyarticular pain with painful tophi (urate deposits) - best seen on tendons and pinna of ear (also in tendons and joints)
summary of gout sx
acute attack
intercritical gout
chronic tophaceous gout
sx of urate urolithiasis, interstitial nephritis
sx of pseudogout
acute arthrits
- monoarthropathy
- painful swollen joint - knee, ankle, shoulder, elbow, wrist
chronic arthropathy
- inflammatory symmetrical polyarthritis and synovitis
- pain
- stiffness
- functional impairment
uncommon presentations
- tendonitis - achilles
- tenosynovitis - tendons of the hand
- bursitis - olecranon bursitis
signs of pseudogout
acute arthritis
- red
- hot
- tender
- restricted range of movement
- fever
chronic arthropathy
- similar to osteoarthritis
- bony swelling
- crepitus
- deformity eg varus knees
- restriction in movement
Ix for gout
synovial fluid aspirate
- diagnosis depends on the presence of monosodium urate crystals which are needle shaped and negatively birefingent under polarised light - yellow and blue
- microscopy and culture - exclude septic arthritis
blood
- FBC - high WCC
- UE
- high urate - may be normal in acute gout
- high ESR
XR - soft tissue swelling in early stages. Later - well defined ‘punched out’ erosions (rat-bite) are seen in juxta-articular bone. No sclerotic reaction - joint spaces are preserved until late
AXR/KUB
- uric acid renal stones - radiolucent
Ix for pseudogout
blood
- FBC - high WCC in acute attack
- high ESR
- blood culture - excludes infective arthritis
joint aspiration
- Microscopy shows short rhomboid brick-shaped crystals, with weak positive birefringence under polarized light.
- Culture or Gram staining (exclude infective arthritis).
plain radiograph of the joint
- chondrocalcinosis - linear calcification of the cartilage
- signs of osteoarthritis - loss of joint space, osteophytes, subchondral cysts, sclerosis
pricipitants for acute gout
trauma
surgery
starvation
infection
diuretics
ddx for gout
septic arthritis
reactive arthritis
haemarthrosis
CPPD
palindromic RA
RF for reduced urate excretion - gout
elderly
men
post-menopausal females
impaired renal function
HTN
metabolic syndrome
diuretics
antihypertensives
aspirin
RF for excess urate production
dietary - alcohol, sweeteners, red meat, sea food
genetic disorders
myelo- nad lymphoproliferative disorders
psoriasis
tumour-lysis syndrome
drugs (alcohol, warfarin, cytotoxics)
associations with gout
CVD
HTN
DM
Chronic renal failure
gout is an independant RF for mortality from cardiovascular and renal disease
Screen for and treat CKD, hypertension, dyslipidaemia, diabetes
prevention of gout
lose weight
avoid prolongued fasts, alcohol excess, purine rich meats and low dose aspirin
Review medications – some reduce urate excretion
Want stop urate production – xanthine oxidase – so use allopurinol to block this = produce less uric acid = fall – below crystalisation point = crystals dissolve and dont get gout
pathophysiology of gout
Purine nucleotides – 2/3 from break down of own body products - Nucleotides broken down into uric acid
Most excreted via kidneys, some through gut
If build up – crystals deposit in joints and soft tissues (in irregular surface)
shed and stimulate acute inflammatory reaction – severe joint pain and tenderness
signs of gout
Feel – warm and tender- wont want to move joints
Uric acid crystal deposition in soft tissue = tophi – can become big, resolve with gout treatment
rat-bite lesion – at the side of the joint
in gout
low purine diet
reduce alcohol - especially beer
avoid fish - anchovies, sardines, herring, mackerel
avoid offal and game
moerate veg - spinach, cauliflower, asparagus, mushrooms
moderate dried veg eg lentils/peas/beans
moderate fish and meat
avoid obesity
pseudogout
chondrocalcinosis due to CCP crystals depositing in the menisci
Mx of acute gout
NSAIDs
Steroids
colchicine
2nd line - interleukin-1 inhibitor
Chronic mx of gout
allopurinol
bridge with NSAIDs/colchicine
