Rheum- Gout

Question 1

What is gout?

Answer 1

• microcystal synovitis

Question 2

What type of cyrstals do you get in gout?

Answer 2

• deposition of monosodium urate monohydrate in the synovium
• Needle shaped negatively bifringent

Question 3

What are causes of gout? / RFs?

Answer 3

• chronic hyperuricaemia
  Decreased excretion of uric acid
• drugs- diuretics
• CKD
• Lead toxicity
  Increased production of uric acid
• myeloproliferative/lymphoproliferative disorder
• cytotoxic drugs
• severe psoriasis

Question 4

What is Lesch- Nyhan syndrome?

Answer 4

• hypoxanthine-guanine phosphoribosyl transferase (HGPRTase) deficiency
• x-linked recessive therefore only seen in boys
• features: gout, renal failure, neurological deficits, learning difficulties, self-mutilation

Question 5

How does gout present?

Answer 5

• episodic flares
• symptom free between episodes
• pain- very signficant
• swelling erythema

QM:
* Bigtoe and the knee are most frequently affected
* Extra-articular attacks can sometimes occur, particularly affecting the olecranon bursae
* sudden, severe attacks of joint pain
* swelling,
* redness
* tenderness
Following acute attacks, symptoms resolve; however, joint damage can occur following recurrent attacks

Question 6

Common areas for gout to affect?

Answer 6

• 1 MTP joint
• Ankle
• Wrist
• Knee

Question 7

Inv for gout?

Answer 7

• Uric acid- >360umol/L
  -< 360umol/L but strong suspicision of gout, repeat uric acid level after the flare has settled
• Synovial fluid analysis- needle shaped negatively bifringent monosodium urate crystals under polarised light
• Xray
• PAINFUL, WARM SWOLLEN JOINT- need to rule out septic arthritis- basic obs, FBC, CRP, U&Es, LFTs, joint aspiration

Question 8

Radiologial features of gout?

Answer 8

• joint effusion is an early sign
• well-defined ‘punched-out’ erosions with sclerotic margins in a juxta-articular distribution, often with overhanging edges
• relative preservation of joint space until late disease
• eccentric erosions
• no periarticular osteopenia (in contrast to rheumatoid arthritis)
• soft tissue tophi may be seen

Question 9

Acute Management of gout?

Answer 9

• NSAIDs or colchicine are first-line
  the maximum dose of NSAID should be prescribed until 1-2 days after the symptoms have settled gastroprotection (e.g. a proton pump inhibitor) may also be indicated
• colchicine - has a slower onset of action
  may be used with caution in renal impairment: the BNF advises to reduce the dose if eGFR is 10-50 ml/min and to avoid if eGFR < 10 ml/min BNF
  the main side-effect is diarrhoea
• oral steroids may be considered if NSAIDs and colchicine are contraindicated.
  a dose of prednisolone 15mg/day is usually used
• another option is intra-articular steroid injection
• if the patient is already taking allopurinol it should be continued

Question 10

When do you offer urate- loweing therapy?

Answer 10

• British Society of Rheumatology Guidelines now advocate offering urate-lowering therapy to all patients after their first attack of gout
  ULT is particularly recommended if:
• > = 2 attacks in 12 months
• tophi
• renal disease
• uric acid renal stones
• prophylaxis if on cytotoxics or diuretics

Question 11

What is the first- line therapy for urate-lowering therapy?

Answer 11

• allopurinol is first-line
• initial dose of 100 mg od, with the dose titrated every few weeks to aim for a serum uric acid of < 360 µmol/l
• lower target uric acid level below 300 µmol/L may be considered for patients who have tophi, chronic gouty arthritis or continue to have ongoing frequent flares despite having a uric acid below 360 µmol/L
• a lower initial dose of allopurinol should be given if the patient has a reduced eGFR
• colchicine cover should be considered when starting allopurinol. NSAIDs can be used if colchicine cannot be tolerated. The BSR guidelines suggest this may need to be continued for 6 months

Question 12

What would you use if allopurinol is ineffective?

Answer 12

• febuxostat (also a xanthine oxidase inhibitor)

Question 13

Lifestyle modifications for gout?

Answer 13

• reduce alcohol intake and avoid during an acute attack
• lose weight if obese
• avoid food high in purines e.g. Liver, kidneys, seafood, oily fish (mackerel, sardines) and yeast products

Question 14

What is pseudogout caused by?

Answer 14

• calcium pyrophosphate dihydrate cyrstals in the synovium

Question 15

What are the RF for pseudogout?

Answer 15

• increasing age
• in younger pts will have other RF:
  haemochromatosis
  hyperparathyroidism
  low magnesium, low phosphate
  acromegaly, Wilson’s disease

Question 16

Features of pseudogout?

Answer 16

• knee, wrist and shoulders most commonly affected
• joint aspiration: weakly-positively birefringent rhomboid-shaped crystals
• x-ray: chondrocalcinosis
• in the knee this can be seen as linear calcifications of the meniscus and articular cartilage

Question 17

Management of pseudogout?

Answer 17

• aspiration of joint fluid, to exclude septic arthritis
• NSAIDs or intra-articular, intra-muscular or oral steroids as for gout