gout Flashcards
what’s gout
Gout is a crystalline joint disease in which a patient exhibits joint pain, swelling and redness.
- Hyperuricaemia is a major risk factor for gout (0.42 mmol/L); deposition of urate crystals in and around joints.
- Recurrent episodes of gout flares can lead to chronic arthropathy, tophi depositions and renal disease.
- It is more common in men, older people and Taiwanese Aboriginals/ Maori/ Pacific Islanders.
What can cause gout?
Disorder of purine metabolism: hyperuricaemia
Overproduction of uric acid: excessive cell turnover (neoplastic disorders) or excessive dietary purines.
Underexcretion of uric acid: renal impairment, obesity or concomitant medications (diuretics).
how can gout be diagnosed?
Crystals in synovial fluid aspirates (but not regularly performed)
Features are highly suggestive: articular involvement such as toe or ankle joint, previous episodes and viewing risk factors.
how can gout be clinically manifested?
Asymptomatic hyperuricaemia (common)
Acute or chronic gout
Chronic tophaceous gout (uric acid crystal deposits)
Gout nephropathy
non-pharm treatment of gout
No evidence that avoiding purine-rich food reduces the risk of gout flares but can reduce uric acid concentrations by 0.02 mmol/L.
Avoid dietary ‘triggers’ of gout flares
Reduce alcohol consumption, particularly binge drinking
Keep well hydrated. I.e. avoid dehydration.
Implement a weight loss program in patients who are overweight.
first line treatment for gout
Relieve pain and inflammation: NSAIDs (including COX-2 inhibitors) and colchicine.
Full dose for the first 24-48 hours then a reduced dose for 7-10 days.
Avoid aspirin as it can affect renal function, reducing uric acid excretion.
For colchicine: 1 mg stat then 0.5 mg one hour later (max 1.5 mg per course). Lower doses are required if renal impairment or receiving CYP3A4 or pgp-inhibitors.
second line treatment for gout
Corticosteroids (for patients who can’t use NSAIDs or colchicine).
Oral, systemic or intra-articular.
IA: Do not give >4 injections/year into any single joint - increases risk of cartilage damage.
Avoid further injections if no response after 2 consecutive injections.
Big toe generally not recommended due to pain
Do not overuse the joint following IA injection
Who or when is prophylactic treatment recc for?
Indicated for tophaceous gout, evidence of radiographic damage attributable to gout or 2 or more gout flares per year.
Conditional recommended for patients who have:
previously experienced >1 flare but have infrequent flares (< 2 p.a.)
Comorbid moderate to severe CKD
Urolithiasis (kidney stones)
list out the meds used in prophylactic treatment of gout
Therapy can include:
Xanthine oxidase inhibitors → reduce the production of uric acid
Allopurinol – preferred
Febuxostat – only if allopurinol CI
Uricosuric agents →increase the renal clearance of uric acid
Probenecid
Benzbromarone (available via SAS)
Preferred concomitant medications for gout
Drugs associated with a reduction in serum urate concentrations.
E.g. Losartan, fenofibrate, SGLT2 inhibitors.
Allopurinol dosing guidelines
Start at 100 mg/day (CKD stage 3; 50 mg/day)
Up titrate based on serum urate concentrations
Doses > 300 mg/day required (even in renal impairment) – max recommended dose is 900 mg.
Allopurinol should not be stopped during a gout flare as serum urate concentrations will increase and a risk of a ppt another gout flare when it is commenced. It is actually ideal to start allopurinol during a gout flare.
Risk of allopurinol hypersensitivity syndrome is increased in carriers of HLA-B5801, most common in asian people (Han Chinese, Korean, Thai).
Avoid allopurinol is HLA-B5801 positive.
Febuxostat dosing guidelines
Available on PBS as an authority required drug.
Eligible for patients:
CI with allopurinol.
documented history of allopurinol hypersensitivity syndrome
intolerance to allopurinol necessitating permanent treatment discontinuation.
Appropriate in patients HLA-B*5801 positive. Start @ 40 mg/day.
Safety concern: risk of CV death.
optimal urate concentration levels
<0.36 mmol/L (<0.30 mmol/L in tophaceous gout)
Probenecid dosing guidelines
Dosage:
Initially 250 mg twice daily for 1 week.
Maintenance, 500 mg twice daily, increasing if necessary every 4 weeks (by increments of 500 mg) up to 2 g daily in divided doses.
Avoid in patients with moderate-severe CKD; urolithiasis
Uricosuric effect is probably reduced
Avoid use if CrCl <10 mL/minute as probenecid is ineffective
