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
Treatment of pseudogout
Joint aspiration with NSAIDs or colchicine
Possibly corticosteroids
5 cardinal signs of inflammation
Acute: Red Hot Swollen Painful Loss of function
Investigations of crystal arthropathies
WCC
Joint fluid aspirate - crystals
Aspirate MCS to exclude septic arthritis
Gout vs pseudogout: which one is usually mono-articular and which is poly-articular
Gout - mono-articular
Pseudogout - poly-articular
Most commonly affected joint in gout
1st MTPJ
Most commonly affected joint in pseudogout
Knee
Crystal formed in gout
Monosodium urate
Crystal formed in pseudogout
Calcium pyrophosphate
Gout vs pseudogout: birefringence
Gout = -ve Pseudogout = +ve
Risk factors of gout
Male Meat/seafood Alcohol Diuretics CKD
Risk factors of pseudogout
Elderly
Dehydration
Illness
Surgery/trauma
Prevention of gout
Allopurinol - decreases blood uric acid levels
Shape of crystal in gout
gout Needle
Shape of crystal in pseudogout
pseduo Rhomboid
