Gout

Question 1

What is gout?

Answer 1

A chronic disease which involves deposition of monosodium urate crystals into soft tissue, joints and kidney

Question 2

What is the most important determinate of developing gout?

Answer 2

Serum uric acid concentration
-Incidence of gout increased exponentially when uric acid levels are >0.54mmol
BUT acute gout can occur with normal serum

Question 3

What is uric acid?

Answer 3

Uric acid is the by product of purine metabolism that occurs in the liver
Purine sources are endogenous and dietary

Question 4

What factors increase uric acid?

Answer 4

Eating purine rich foods such as

• Seafood
• Meat
• Alcohol (esp beer and spirits)
• Fructose sweetened drinks

Disorders of high cell turnover

• Haem malignancies
• Psoarisis

Anything that blocks renal excretion of uric acid

Question 5

What can disrupt kidney uric acid excretion?

Answer 5

Drugs:

• Thiazide diuretics (common 2ndary gout)
• Loop diurectics
• Cyclosporins

Conditions: (are risk factors for gout))

• DM
• HTN
• Dyslipidemia
• CKD
• Obesity (because high insulin levels)
• Sepsis
• Dehydration

Question 6

How does acute gout present?

Answer 6

Monoarticular (1st MTP or other part of foot)

• Red
• Swollen
• severe pain
• joint mobility may be limited

But can subside within days to weeks

Question 7

How does chronic gout present?

Answer 7

1. Can be oligoarticular or polyarticular
2. Can have symmetrical involvement of small joints of hands (can mimic rheumatoid and psoriatic arthritis)
3. Gouty tophi
   - elbows (olecranon bursae)
   - knees (prepatellar bursae)
   - peripheral joints (fingers & toes)

Question 8

What is the pathogenesis of chronic gout?

Answer 8

Recurrent attacks
Urate crystals deposit in soft tissue, joints, kidneys

Leads to joint arthritis and chronic kidney disease

Question 9

What investigations would you do for gout?

Answer 9

a) Joint aspirate
b) Xrays
- show soft tissue swelling
- punched out lesions- erosions
c) serum uric acid concentration- but not diagnostic

Question 10

What is the management of acute gout?

Answer 10

1. NSAIDS: naproxen, ibuprofen, indomethacin
   OR
2. Prednisone: 15-30mg PO for 3-5 days
   OR
   3.Corticosteroid injections: local max two sites
   OR
3. Colchicine: 1mg PO initially then 500mcg 1 hour later as a single one-day course

Question 11

What is required for definitive diagnosis of gout?

Answer 11

Joint aspirate

• show monosodium urate crystals
• negative birefringent and needle shaped

Once definite diagnosis made, diagnostic aspiration not needed for recurrent attacks

Question 12

What is the management of chronic gout?

Answer 12

1. First line urate lowering therapy
   - Allopurinol monotherapy
   - Allopurinol + Probenecid
2. Second line (when Allopurinol counter-indicated)
   - Probenecid
   - Febuxostat

Question 13

What is the mechanism of action of allopurinol?

Answer 13

Xanthine oxidase inhibitor
Which inhibits the synthesis of uric acid
Purine–>hypoxanthine–>xanthine–>uric acid

Question 14

What are symptoms of intolerance to allopurinol?

Answer 14

Rashes- maculapapular
Hepatotoxicity
Allopurinol hypersensitivity syndrome: fever, rash, hepatitis

Question 15

When you have started patient on allopurinol, what needs to be measured and titrated?

Answer 15

In the first month the dose of allopurinol should be titrated with serum uric acid concentration

Question 16

What is the target serum uric acid concentration for treatment with allopurinol?

Answer 16

• Serum Uric acid <0.36mmol/L

- If tophi present then target <0.30mmol/L

Question 17

What is important in patient education when starting chronic gout treatment?

Answer 17

Life long adherence

The risk of flares when starting or increasing urate lowering therapy

Question 18

What is the dose of allopurinol?

Answer 18

50mg PO daily for 4 weeks

• Then increase the dose by 50mg every 2-4 weeks Or
• Increase by 100mg every 4 weeks

BUT max dose 900mg daily

=To achieve the target uric acid concentration

Question 19

If a patient has a acute flare whilst on chronic gout management how should it be treated?

Answer 19

Continue urate lowering therapy (allopurinol etc)

Add tx for acute gout flare (NSAID, colchicine, prednisone)

Question 20

As there is a high risk of flares when starting or increasing urate lowering therapy, what can you do to minimise this risk?

Answer 20

Flare prophylaxis

• Colchicine 500mg daily once or BD OR
• NSAID PO OR
• Prednisone 5mg PO daily

Prophylaxis should be used for at least 6 months