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Gout
Last updated 11th April 2024
Diagnosis
- Use the EULAR/ACR Classification criteria for gout. There are several on-line calculators: a score of 8 or more is gout Gout Classification Calculator
Mechanisms
- Under secretion of urate is most common – thiazides, alcohol, impaired renal function.
- Over production of urate – myeloproliferative disorders especially when treated, psoriasis.
Triggers of Acute Attack
- Acute attacks often triggered by sudden changes in serum urate, which can be up or down
- Common triggers are dehydration, trauma, surgical operations, initiation of allopurinol, alcohol, stopping or starting diuretics.
Differential Diagnosis
- Pseudogout – often presents as hot swollen knee in elderly with OA. Chondrocalcinosis on X-ray & rhomboid crystals of calcium pyrophosphate in synovial fluid.
- Septic arthritis – note leucocytosis & fever may also occur in gout.
Management of Acute Attack
- Treat as soon as possible with NSAIDs or Colchicine or steroids.
- Allopurinol should not be commenced during an acute attack but in patients already established on allopurinol, it should be continued and the acute attack treated conventionally
- Opiate analgesics can be used as adjuncts
- Rest, cold packs and splintage can be helpful
When to Consider Prophylaxis
- In uncomplicated gout if second or further attacks within 1 year
- With visible gouty tophi
- With renal insufficiency – eGFR <60ml/min
- With uric acid stones
How to do Prophylaxis
- Allopurinol is the first choice urate lowering drug, Febuxostat and the Uricosuric agents, covered by NSAID +/- PPI for 6 weeks or Colchicine for up to 6 months – in practice most patients choose to take NSAIDs/Colchicine if/when an acute attack occurs
- Aim to maintain serum urate <0.36 mmol/l, or below 0.30 mmol/l if tophi present
- Delay starting uric acid-lowering drug therapy until 1-2 weeks after inflammation has settled
- Follow up by rheumatology recommended
NSAIDs
- First line therapy for acute attack unless contraindicated because of renal failure, heart failure, active peptic ulcer or known NSAID intolerance.
- Use fast acting NSAID at maximum dose eg ibuprofen 400-600mg tds or Etoricoxib 120mg od.
- Coprescription of PPI should follow standard advice for use of NSAIDs and Coxibs in patients with increased risk of peptic ulcers, bleeds and perforations
Colchicine
- Used both in treatment of acute gout and for prevention. Frequently given for up to 6 months to prevent acute attacks during initiation of urate lowering therapy
- Starting dose in acute gout is 1mg stat then 0.5mg tds until attack resolves or patient develops side effects.
- Prophylactic dose is 0.5mg bd for patients with normal renal function
- Lower prophylactic doses should be given to patients with renal failure eg 0.5mg od or every other day if eGFR 30-59ml/min and 0.5mg every 2-3 days if eGFR <30ml/min.
- Common side effects are vomiting and diarrhoea which are dose related and resolve with dose reduction.
- Important drug interaction with CYP450 3A4 inhibitors esp clarithromycin, simvastatin/atorvastatin, protease inhibitors and azole antifungals which can lead to life threatening neutropenia
Steroids
- Consider Prednisolone 30mg od orally for the duration of an acute attack in patients who cannot take NSAIDs or Colchicine. Rx for maximum 7 days. Most need 3-5 days only. The drug should be stopped and not tapered
- Intra-articular steroid highly effective in acute gouty monarthritis
Allopurinol
- Xanthine oxidase inhibitor – inhibits production of uric acid.
- First line therapy for prevention of recurrent gout.
- Has no place in management of acute gout and may even trigger an acute attack if given alone so is usually co-prescribed initially with NSAID or colchicine
- Starting dose is 100mg daily
- Dose should be titrated by increments of 100mg every 2-3 weeks to max of 900mg daily if necessary and if tolerated in order to achieve serum uric acid <0.36mmol/l
- Most important side effect is a skin rash that may vary in severity from mild and remitting with reduction in dose to severe and life threatening including toxic epidermal necrolysis and Stevens-Johnson syndrome.
- Important drug interaction with azathioprine that can lead to life threatening neutropenia. Options are to reduce dose of Azathioprine by 75% or switch to mycophenolate which does not interact with allopurinol
Febuxostat
- Another xanthine oxidase inhibitor
- Second line therapy for prevention of recurrent gout in patients unable to tolerate allopurinol
- Starting dose 80mg daily, maximum 120 mg daily
- Side effects and drug interactions as per allopurinol
Uricosuric Agents
- Uricosuric agents are now rarely used
Aspirin
- Aspirin 75-150mg daily has no anti-inflammatory effect and no effect on serum urate.
- Aspirin in analgesic doses of 600-2400mg/day has paradoxical effects on serum urate – raises it at lower doses and uricosuric at higher doses – and should be avoided
Lifestyle advice for all patients
- Aim for ideal body weight
- Encourage moderate physical exercise
- Restrict alcohol intake <14 units, with at least 3 alcohol free days each week
- Drink at least 2 litres of fluid per day
Role of Low Purine Diet
- Some restriction of purine intake is helpful in many patients and especially in patients with renal insufficiency.
- Purine contents of various foods can be found online eg www.ukgoutsociety.org
- In practice a total daily purine intake of around 200mg can usually be achieved by avoiding foods with very high purine content and moderating intake of foods with relatively high purine content
Links
Content Updated by Dr Lucy Moran