Crystal Arthropathy Flashcards
What is gout?
a disorder of uric acid metabolism causing recurrent bouts of acute arthritis caused by deposition of monosodium urate crystals in joints, soft tissues + kidneys
What is the main metabolic disturbance causing gout? What may this be caused by?
Hyperuricaemia
Increased urate intake or production
Decreased Renal Excretion
List 3 causes of increased urate intake or production
Increased dietary intake
Increased nucleic acid turnover (e.g. lymphoma, leukaemia, psoriasis)
Increased synthesis of urate (e.g. Lesch-Nyhan syndrome)
List 3 causes of decreased renal urate excretion
Idiopathic
Drugs (e.g. ciclosporin, alcohol, loop diuretics)
Renal dysfunction
Describe the epidemiology of gout
M»_space; F
Very rare pre-puberty
Rare in pre-menopausal women
More common in HIGHER social classes
List 5 precipitating factors of gout
Trauma Infection Alcohol Starvation Introduction or withdrawal of hypouricaemic agents
What is the main symptom of gout?
Sudden excruciating monoarticular pain
Usually affecting the metatarsophalangeal joint of the great toe (podagra)
Describe the nature of symptoms in gout
Symptoms peak at 24 hrs
Resolve over 7-10 days
Sometimes, acute attacks can present with cellulitis, polyarticular or periarticular involvement
Attacks are often recurrent
Patients are symptom-free between attacks
What is Intercritical Gout?
asymptomatic period between acute attacks
When does Chronic Tophaceous Gout occur? What symptoms are caused?
Follows repeated acute attacks Symptoms: Persistent low-grade fever Polyarticular pain with painful tophi (urate deposits) Best seen on tendons + pinna of the ear
What investigation is used to diagnose gout? What is seen? What is this sample used for?
Synovial Fluid Aspirate
Monosodium urate crystals
Microscopy + culture to exclude septic arthritis
Describe monosodium urate crystals
Needle-shaped
NEGATIVE birefringence under polarised light microscopy
What bloods are seen in gout?
FBC: raised WCC
U+Es
Raised urate
Raised ESR
What may be seen on AXR/KUB Film in gout?
Uric acid renal stones may be seen
What is pseudo gout?
arthritis associated with deposition of calcium pyrophosphate dihydrate (CPPD) crystals in the joint cartilage
Describe the pathophysiology of pseudogout
CPPD crystal formation is initiated in cartilage located near the surface of chondrocytes
Linked with excessive calcium pyrophosphate production: Abundance leads to formation of CPPD crystals
Shedding of crystals into the joint cavity leads to acute arthritis
What predisposes to pseudo gout?
Most causes of joint damage (e.g. osteoarthritis, trauma)
List 4 conditions that increase risk of pseudo gout
Haemochromatosis
Hyperparathyroidism
Hypomagnesaemia
Hypophosphatasia
List 3 precipitating factors of pseudogout
Intercurrent illness
Surgery
Local trauma
Describe the epidemiology of pseudogout
F > M
More common in the ELDERLY
What symptom of acute arthritis is seen in pseudogout?
Painful swollen Joint (e.g. knee, ankle, shoulder, elbow, wrist)
List 3 symptoms of chronic arthropathy in pseudogout
Pain
Stiffness
Functional impairment
List 3 rarer symptoms of pseudogout
Tendonitis
Tenosynovitis
Bursitis
List 5 signs of acute arthritis in pseudogout
Red Hot Tender Restricted range of movement Fever
List 4 signs of chronic arthropathy in pseudogout
Similar to osteoarthritis Bony swelling Crepitus Deformity Restriction of movement
What bloods should be taken in pseudogout?
High WCC in acute attacks
High ESR
Blood culture: to exclude septic arthritis
What is seen on joint aspiration in pseudogout?
Rhomboid, brick-shaped crystals
POSITIVE birefringence
Culture or Gram-staining to exclude septic arthritis
List 5 features seen on radiographs in pseudogout?
Chondrocalcinosis Loss of joint space Osteophytes Subchondral cysts Sclerosis
