Crystal Arthropathies Flashcards
Define gout
Disorder of uric acid metabolism leading to monosodium urate crystal deposition in the joints, soft tissues and kidneys, causing recurrent bouts of acute arthritis.
Aetiology of gout
Underlying metabolic disturbance is hyperuricaemia, which may be caused by:
→ Increased urate intake or production (10%): Increased dietary intake, increased purine turnover (lymphoma, leukaemia, polycythaemia vera, psoriasis), increased synthesis in Lesch-Nyhan syndrome**
→ Decreased renal excretion (90%): Idiopathic, drugs*, renal dysfunction
*CANT LEAP (Ciclosporin, alcohol, nicotinic acid, thiazides, loop diuretics, ethambutol, aspirin, pyrizanamide
**Lesch–Nyhan syndrome (gout + mental retardation + self- mutilating behaviour)
Acute (Podagra) or chronic (Tophaceous)
Risk factors for gout
Dietary factors (seafood, meat and alcohol (esp. beer) consumption
Older age
Male sex
Menopausal
Drugs (CANT LEAP)
Obesity (adiposity)
Insulin resistance
Hypertension
Renal insufficiency
Hyperlipidaemia
Family history
Symptoms of gout
Episodes of pain (acute attack)
- Rapid onset
- Severe/excruciating
- Monoarticular
- Commonly the first metatarsophalangeal joint
- Peak at 24 hours, resolve in 7-10 days
- Precipitated by trauma, infection, alcohol, introduction or withdrawal of hypouricaemic agents
- Asymptomatic between acute attacks (intercritical gout)
Joint stiffness
Swelling
Tenderness
Chronic tophaceous gout: follow repeated acute attacks - persistent low-grade fever, polyarticular pain with painful tophi on the tendons and pinna of ear
Symptoms of urate urolithiasis (kidney involvement)
Signs of gout on examination
Tophi
Joint stiffness
Foot joint distribution
Swelling and join effusion
Erythema and warmth
Investigations for gout
Bloods only, further Ix in secondary care if uncertain or unconfirmed
Uric acid: raised >416 (M) or >360 (F), usually 2 weeks after an attack
FBC: Raised WCC
ESR: raised
Renal screen: ?CKD
Arthrocentesis with synovial fluid analysis: raised WCC, negatively birefringent needle-shaped crystals under polarised light with red filter (blue needles, left→ right)
MC&S synovial fluid: negative
US: erosions, tophi, double contour line
X-ray affected joint: peri-articular lesions, ‘rate bite’ erosions
Management for acute gout attacks
- NSAIDs e.g. naproxen 500mgs bd (do not give if CKD is the cause of gout)
- Colchicine 500mcg 2x a day (inhibit microtubule assembly in neutrophils by inhibiting tuberculin)
- Glucocorticoids e.g. prednisolone 15-20mgs for 7 days / intra-articular steroids
All 3 contraindicated → IL-1 inhibitor
+ Advice:
- Apply ice packs to the joint
- Use paracetamol
- Education on gout
- Rest and elevate
- Keep joint exposed and in a cool environment
- Return if symptoms get worse or there is not improvement after 1-2 days
Follow-up in 4-6 weeks and check BP, HbA1c, serum urate, U&Es, lipids → consider ULT
Management between attacks for gout
Conservative
- Hydrate
- Reduce purine intake: anchovies, sardines, mackerel, offal, game
- Moderate spinach, cauliflower, asparagus, mushrooms, lentils/peas/beans, meat, fish
- Avoid alcohol
- Avoid prolonged fasting
Medical: urate lowering therapy
- Allopurinol (reduce synthesis; ok in CKD, Does not need to be stopped if already established), Febuxostat
- Probenecid (increase urate excretion; only give if GFR >50), losartan
- Recombinant urate oxidase: rasburicase
Complications of gout
Chronic arthritis if untreated (2%)
Joint damage
Reduced QOL
Renal stones
Tophi -> inflammation, exudative, secondary infection
Cardiovascular disease and mortality
Ass. With CKD
Prognosis for gout
Acute attacks are self-limiting, if untreated with resolve spontaneously over 5-15 days (+ pruritus and desquamation of overlying skin)
Risk of recurrence is 62% without urate lowering therapies (ULT) in the first year, 78% in the second and 84% in the third year
Treatment can suppress attacks and recurrence
What is pseudogout
arthritis associated with deposition of calcium pyrophosphate dihydrate (CPPD) crystals in joint cartilage
What is the aetiology and risk factors of pseudogout
May be predisposed by osteoarthritis, trauma, haemochromatosis, hyperparathyroidism, hypomagnesaemia, hypophosphatasia
CPPD crystals formed in cartilage near chondrocyte surface → excessive production and deposition → sheds into joint cavity → arthritis
RF:
- older age
- injury
- hyperPTH
- haemochromatosis
- HypoMg/PO4
Symptoms and signs of pseudogout
Painful and tender joints
- Acute - larger joints: painful, swollen knee, ankle, shoulder, elbow, wrist
- Chronic: pain, stiffness, functional impairment
Sudden worsening of osteoarthritis
Red and swollen joints
Fever and malaise
Tendonitis, tenosynovitis, bursitis (rare)
Acute arthritis: Red, hot, tender, restricted range of movement, fever
Chronic arthropathy: bony swelling, crepitus, deformity, restriction of movement
Investigations for pseudo gout
Bone profile: raised Ca, PTH deranged
U&Es: hypoMg/PO4
FBC: raised WCC
ESR: raised
Arthrocentesis with synovial fluid analysis: pyrophosphate rhomboid crystals positive birefringence under polarised light
X-ray affected joint: linear, stippled radio-opaque deposits in the fibro-cartilate/hyaline articular cartilage + osteoarthritic changes (LOSS)
Management for pseudogout
Analgesia
NSAIDs
PO/IM/intra-articular steroids
Colchicine
Symptomatic relief: cool pacts, temporary rest
