Crystal arthropathy (gout, pseudogout) Flashcards
Define gout
A disorder of uric acid metabolism causing recurrent bouts of acute arthritis caused by deposition of monosodium urate crystals in joints, and also soft tissues and kidneys
Explain the aetiology/risk factors of gout
The main metabolic disturbance is hyperuricaemia
This may be caused by:
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)
Decreased Renal Excretion
Idiopathic
Drugs (e.g. ciclosporin, alcohol, loop diuretics)
Renal dysfunction
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
Precipitating factors of Acute Gout
Trauma Infection Alcohol Starvation Introduction or withdrawal of hypouricaemic agent
Recognise the presenting symptoms and signs
of gout
Acute Attack
Sudden excruciating monoarticular pain, Usually affecting the metatarsophalangeal joint of the great toe (podagra)
Symptoms peak at 24 hrs
They 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 attack
Intercritical Gout - DEFINITION: asymptomatic period between acute attacks
Chronic Tophaceous Gout
Follow repeated acute attacks
Symptoms:
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)
Identify appropriate investigations for gout
Synovial Fluid Aspirate - 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
Bloods FBC-raised WCC U&Es Raised urate Raised ESR
AXR/KUB Film - Uric acid renal stones may be seen
Define pseudogout
Arthritis associated with deposition of calcium pyrophosphate dihydrate (CPPD) crystals in the joint cartilage
Explain the aetiology/risk factors for pseudogout
CPPD crystal formation is initiated in cartilage located
near the surface of chondrocytes
It is linked with excessive calcium pyrophosphate production. This 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)
Rarer conditions that increase the risk of pseudogout: Haemochromatosis Hyperparathyroidism Hypomagnesaemia Hypophosphatasia
Precipitating factors:
Intercurrent illness
Surgery
Local trauma
Summarise the epidemiology of pseudogout
2 x more common in WOMEN
More common in the ELDERLY
Recognise 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
Recognise the signs of pseudogout on physical examination
Acute Arthritis - Red, Hot, Tender, Fever, Restricted range of movement
Chronic Arthropathy -Similar to osteoarthritis Bony swelling Crepitus Deformity Restriction of movement
Identify appropriate investigations for pseudogout
Bloods - High WCC in acute attacks, High ESR
Blood culture - to exclude septic arthritis
Joint Aspiration - Rhomboid, brick-shaped crystals, POSITIVE birefringence
Culture or Gram-staining to exclude septic arthritis
Plain Radiograph of the Joint
Chondrocalcinosis
Signs of Osteoarthritis
