Gout Flashcards
How should you dose allopurinol in CKD?
Smaller initial dose (e.g. 50 mg daily or 2nd daily) and slower increments to reach maximal dose
What is the reason for increased flares when starting allopurinol?
Allopurinol lowers serum uric acid . This causes movement of precipitated MSU crystals which makes it more prone to immune recognition, leading to a flare
Gout is rare in men < 25 and pre-menopausal women. True or false?
True.
Common in older men, Pacific Islanders and SE Asians. Estogren is uricoseric and hence lower incidence in pre-menopausal women.
What are the causes of hyperuricaemia ?
Urate overproduction: dietary purines, accelerated ATP degradation in heavy alcohol use, increased nucleotide turnover in haem disease
Urate under-excretion 90% caused by this
CKD, medications (HCT, diuretics)
What is immune pathway that causes gout?
MSU crystals detected by TLR 2 and TLR 4 –> pro-inflammatory cytokines —> inflammatory response.
Coated with IgG –> inflammatory response
Coated with apolipoprotein –> undergo phagocytosis –> induce less inflammation
What are the risk factors for gout?
Renal impairment, alcohol, medications (diuretics, tacrolimus, cyclosporin, low dose aspirin) diet, male gender, older age, family history, ethnic background
What is the most commonly affected joint in gout?
1st MTP (50% cases)
Following that, ankles and knees
Involvement of hands, wrist and elbows - suggests severity
What are clinical features of gout?
Rapid onset of painful, warm, erythematous and swollen joint with fevers
Presence of tophi is a sign of chronicity and severity
How does gout cause renal disease?
Urate nephropathy
1) MSU in interstitial tissues (slower decline in renal function)
2) MSU in collecting ducts and ureters (usually TLS) –> AKI and CKD
Uric acid nephrolithiasis - uric acid stones (10-25% gout patients)
How is gout diagnosed?
Gold standard is joint aspiration showing MSU crystals - needle shaped and neg birefringent
Why is serum uric acid often normal during a flare?
Flare causes inflammation involving IL-6 which is uricosuric - paradoxically low or normal uric acid
What is seen on imaging with gout?
X ray changes are late
- tophi cause soft-tissue shadowing
- periarticular “rat-bite” erosions
US: double contour sign around articular margin
DECT: allows urate crystals to be identified, only validated for feet
How is gout managed?
Aim is to reduce serum uric acid
Saturation point is 0.40
Targets:
- no tophi/erosions aim <0.36
- tophi or erosions < 0.30
Urate-lowering therapy
Flare prophylaxis
Flare management
Metabolic management
Dietary suggestions
What are management options for flares?
NSAIDS (indomethacin, shorter acting - ibuprofen, diclofenac)
Colchicine - 0.5 mg daily or BD- most effective in first 36 hours
Prednisone 0.25-0.5 mg/kg for 5 days then wean
IA steroids
IL-1 antagonist (anakinra) and ACTH
Medications with mild uricosuric effects
amlodipine , losartan, fenofibrate, leflunomide, atorvastatin, rosuvastsatin
