Crystal arthropathy Flashcards
Define gout?
disorder of uric acid metabolism causing recurrent bouts of acute arthritis caused by deposition of monosodium urate ( MSU) crystals
what is pseudogout?
form of arthritis that results from the deposits of calcium pyrophosphate dehydrate crystals- commonly affectes knees and wrists
outline the aetiology of gout?
metabolic distubrance caused by hyperuricaemia
caused by increased urate intake or production
- increased dietary intake ( seafood, red meat, alcohol)
- increased nucleic acid turnover ( Lymphoma, leukaemia, psoriasis)
- increased synthesis of urate ( Lesch- Nyhan syndrome)
Decreased renal excretion
- idiopathic
- drugs ( Cyclosporin, alcohol, loop diuretics, aspirin, salicyclates)
- renal dysfunction)
what are the risk factors for gout?
Older age (peak in males: 40-60yrs; peak in females: 50-70yrs)
Male
Menopause(very rare in pre-menopausal women)
Thiazide and loop diuretics use
Pyrazinamide (used to treat TB) – increases urate reabsorption
Genetic susceptibility
Insulin dependence
Met syndrome
what are the rarer conditions that increase the risk of pseudogout?
o Haemochromatosis
o Hyperparathyroidism
O hypothyroidism
O acromegaly
o Hypomagnesaemia
o Hypophosphatasia
what are the precipitating factors of pseudogout?
Intercurrent illness
Surgery
Local trauma (especially of the meniscus of the knee)
outline the aetiology of pseudogout?
- CPPD crystal formation is initiated in cartilage located near the surface of chondrocytes
- linked with excessive calcium pyrophosphate production
- abundance of calcium pyrophoshpate leads to the formation of CPPD crystals
- Shedding of crystals in to the joint cavity leads to acute arthritis
- Most causes of joint damage predispose to pseudogout (e.g. osteoarthritis, trauma)
- More common in older individuals; seems to be more likely with a FH
summarise the epidemiology of gout?
- 10 x more common in MALES
- Very rare pre-puberty
- Rare in pre-menopausal women
- More common in HIGHER social classes
summarise the epidemiology of pseudogout?
- 2 x more common in WOMEN
- More common in the ELDERLY
what are the precipitating factors of an acute attack of gout?
- Trauma
- Infection
- Alcohol
- Starvation
- Introduction or withdrawal of hypouricaemic agents
what are the symptoms of an acute attack of gout?
- Sudden excruciating monoarticular pain- Usually affecting the metatarsophalangeal joint of the great toe (podagra)
- Symptoms peak at 24 hrs
- Resolve over 7-10 days
- Sometimes, acute attacks can present with cellulitis, polyarticular or periarticular involvement – joint stiffness and swelling (usually monoarticular or oligoarticular – v.few joints affected)
- Attacks are often recurrent
- Patients are symptom-free between attacks
what is intercritical gout?
asymptomatic period between acute attacks
what is chronic trophaceous gout
Follow repeated acute attacks
what are the symptoms of chronic trophaceous gout?
- Persistent low-grade fever
- Polyarticular pain with painful tophi(urate deposits) - Best seen on tendons and the pinna of the ear
- Symptoms of urate urolithiasis (renal calculi symptoms)
what are the presenting symptoms of pseudogout?
Acute Arthritis
- Painful
- Swollen Joint(e.g. knee, ankle, shoulder, elbow, wrist)
Chronic Arthropathy
- Pain
- Stiffness
- Functional impairment
Uncommon Presentations
- Tendonitis
- Tenosynovitis
- Bursitis
what are the signs of pseudogout on physical examination?
Acute Arthritis
- Red
- Hot
- Tender
- Restricted range of movement
- Fever (uncommon)
Chronic Arthropathy
- Similar to osteoarthritis
- Bony swelling
- Crepitus
- Deformity
- Restriction of movement
what is the first line investigation for gout and interpret the results
Synovial Fluid Aspirate (athrocentesis with synovial fluid analysis
Monosodium urate crystals will be seen
They are:
- Needle-shaped
- NEGATIVE birefringence under polarised light microscopy
Microscopy and culture will also be performed to exclude septic arthritis
what investigations would you consider for gout?
bloods
AXR/KUB film
describe the bloods for gout?
FBC - raised WCC
U&Es
Raised urate (not raised in an acute situation)
Raised ESR
what may seen on the AXR/KUB in gout?
- Uric acid renal stones may be seen
- May also want to XR the affected joint
what are the 2 first line investigations for pseudogout?
Joint Aspiration
plain radiographs of joint
describe the joint aspiration in pseudogout?
Rhomboid, brick-shaped crystals
POSITIVE birefringence
Culture or Gram-staining to exclude septic arthritis
describe the plain radiograph of the joint in pseudogout?
chondrocalcinosis
describe bloods in pseudogout?
High WCC in acute attacks
Serum Calcium and PTH (may be normal or elevated in pseudogout)
Iron studies (may be normal or elevated)
Serum Magnesium (may be normal or low)
Serum ALP (may be normal or low)
Blood culture - to exclude septic arthritis
