Gout & Pseudo-gout Flashcards
Define Gout
- Disorder of purine metabolism
- Characterised by
- Hyperuricaemia
- Urate crystal deposition in joints and other tissues
- May result in an inflammatory arthritis
It is the commonest form of arthritis, affecting 2.5% of the UK
Describe the illness course of gout
- Long period of asymptomatic hyperuricaemia
- Acute attacks of gouty arthritis
- Inbetween variable asymptomatic intervals
- Chronic tophaceous gout
List five risk factors for gout
-
Hyperuricaemia
- CKD; HTN; dehydration; diuretics
- Hyperparathyroidism; Down’s syndrome; sarcoidosis
- Male; menopausal: Oestrogen is protective
- Middle age
- FHx
- Ethnicity: hyperuricaemia is commoner is certain groups
- Obesity; metabolic syndrome: produces more urate
- Excess alcohol consumption
- High purine diet eg. red meat, oily fish
Name three complications of gout
- Tophi: typically 10+ years after first attack
- Functional impairment of ADLs; reduced QoL
- Inflammation and exudation of tophaceous material
- Secondary infection
- Renal stones
- CKD; MI: gout is an independent risk factor
- HTN; hyperlipidaemia
- OA
- Obesity; diabetes
Describe the presentation of acute gout
Acute attacks self-limiting within 1-2 wks
- Mono-arthropathy (90%)
- First MPJ most commonly
- Sudden onset agonising joint pain
- Joint tenderness and swelling, peaking within 24h
- May be precipitated by:
- Excess food; alcohol; high fructose
- Dehydration
- Diuretics; ACEi; B-blockers; ciclosporin
Request three investigations for suspected gout
-
Joint aspiration and polarised light microscopy
- Negatively bi-refringent urate crystals
-
Serum uric acid: usually >600mcgmol/L
- Measured 4-6wk after an acute attack
- Monitor cardiovascular risk factors and renal disease
- Lipid profile; HbA1c; BP; BMI
- U+Es; creatinine; eGFR
- LFTs: Chronic alcohol use has raised GGT
- USS: soft tissue swelling
- X-ray: soft tissue swelling, punched-out periarticular erosions
What differential must be excluded in suspected gout?
Septic arthritis
What radiological features are seen in gout?
- Soft tissue swelling (early)
- Punched-out peri-articular erosions (late)
Outline the treatment of acute gout
- Self-care
- Rest and elevate limb
- Avoid trauma
- Expose joint in cool environment; ice pack
- NSAID + PPI (continue for 1-2d post attack) or colchicine
- Consider joint aspiration and intra-articular corticosteroids
Do not stop allopurinol or febuxostat if already established
Outline the prevention of gout
- Lifestyle:
- Weight loss if overwieght; exercise; smoking cessation
- Fluid intake; avoid XS alcohol and purine-rich food
-
Urate-lowering therapy (ULT): after acute attack resolved
- Allopurinol
- Febuxostat
- Consider short-term colchicine (up to 6/12)
- Prophylaxis against attacks secondary to ULT changes
ULT is lifelong and requires regular monitoring
Describe the mechanism of action of Colchicine
Prevents urate crystal deposition in joint tissues
What significant interaction may occur between allopurinol and azathioprine?
Pancytopenia
Define Calcium pyrophosphate dihydrate deposition (CPPD) arthopathy
An inflammatory arthritis caused by deposition of calcium pyrophosphate dihydrate crystals.
Commonest cause of articular calcification
3rd commonest cause of inflammatory arthritis
State three differences between gout and pseudogout/CPPD
- Gout:
- Deposition of uric acid crystals
- Negatively bi-refringent needle crystals
- Typically affects middle-aged men
- 1st MTP joint
- CPPD:
- Deposition of calcium pyrophosphate dihydrate
- Weakly positive bi-refringent rhomboidal crystals
- More common in elderly women
- Knee, wrist, shoulder
Name three risk factors for CPPD
- Increasing age
- Osteoarthritis
- Joint trauma
- Metabolic disease:
- Hyperparathyroidism
- Haemochromatosis
- Hypomagnesaemia: Mg2+ helps Ca2+ absorption
- FHx
- Elderly women
Request two investigations for CPPD
- Joint aspiration and microscopy
- Weakly positive bi-refringent rhomboidal crystals
- Joint X-ray: cartilage calcification
