Crystal Arthropathies Flashcards
Types
Gout
Pseudogout
What is gout
deposition of monosodium urate monohydrate (uric acid) crystals within joints
Gout pathophysiology
Monosodium urate (derived from purine breakdown) precipitates and forms deposits in joints.
Crystals formed are very painful.
Can form tophi; asymmetrical chalky appearance, firm nodules
Clinical presentation of gout
A joint becomes swollen, tender and erythmatous (redness of skin).
Florid synovitis, extreme tenderness.
Usually affects the metatarsalphalangeal joint of the big toe.
Painful!
Aetiology of gout
Hyperuricaemia.
Often idiopathic Impaired excretion: CKD, diuretics, hypertension
Increased uric acid production (rarer): PPS overactivity, increased turnover
Epidemiology of gout (risk factors)
Much more common in males
RFs: Meat, seafood, alcohol, diuretics
Diagnostic tests of gout
Joint fluid microscopy - MSU negatively birefringent needle crystals
Examination - tophi confirm diagnosis
Treatment of gout
Acute: ice pack, rest, elevation
NSAIDs (diclofenac)
Colchicine (if can’t use NSAIDs)
Long term: Allopurinol (prevention)
Complications of gout
Nephrolithiasis, infection
Recurrence, usually within first year
What is pseudogout
Deposition of calcium pyrophosphate (dehydrate) crystals within joints
Pathophysiology of pseudogout
Excess of pyrophosphate and calcium in the blood -> crystal deposition in synovium
Clinical presentation of pseudogout
Often asymptomatic.
Joints become swollen tender and erythmatous (as above).
Usually affects knee or wrist.
In chronic condition, destructive changes as in OA.
Aetiology of pseudogout
Unknown.
Precipitated by dehydration, steroids, hyperparathyroidism.
In younger patients, associated with; haemochromatosis and wilson’s disease.
Epidemiology of pseudogout
Usually affects elderly women
Diagnostic tests of pseudogout
Joint fluid microscopy - rhomboid positively birefringent crystals
