Gout

Question 1

What is gout?

Answer 1

Inflammatory crystal arthropathy caused by precipitation + deposition of uric acid crystals in synovial fluid + tissues

Question 2

What is the broad cause of gout?

Answer 2

Hyperuricaemia
Decreased uric acid excretion (90%)
or
Increased production (10%)

Question 3

List 3 causes of decreased uric acid excretion

Answer 3

Drugs
CKD
Lead nephropathy

Question 4

List 4 drugs that decrease uric acid excretion

Answer 4

Aspirin
Thiazide diuretics
Loop diuretics
Pyrazinamide

Question 5

List 3 causes of increased uric acid production

Answer 5

High cell turnover
Enzyme defects
Diet rich in protein (esp. purine)

Question 6

List 4 causes of high cell turnover that can increase uric acid production

Answer 6

Tumor lysis syndrome
Myeloproliferative/ lymphoproliferative disorders
Psoriasis
Chemo/ Radiation

Question 7

Name a syndrome with enzyme defects causing increased uric acid production

Answer 7

Lesch-Nyhan syndrome
X-linked recessive (only seen in boys)
Hypoxanthine-guanine phosphoribosyl transferase (HGPRTase) deficiency

Question 8

List 5 features of Lesch-Nyhan syndrome

Answer 8

Gout
Renal failure
Neurological deficits
Self-mutilating behaviour
Learning difficulties

Question 9

List 4 types of food rich in purines

Answer 9

Meat (Liver, Kidneys)
Seafood
Oily fish (Mackerel, sardines)
Yeast products

Question 10

What can cause combined decreased excretion and overproduction of uric acid predisposing to gout?

Answer 10

High alcohol consumption esp. beer

Question 11

How does weight impact levels of uric acid?

Answer 11

Higher BMI correlates with higher uric acid levels, regardless of dietary habits.

Question 12

Describe onset of episodes of gout

Answer 12

Acute
Typically max. intensity within 12h

Question 13

Give 3 S/S of gout

Answer 13

Pain +++
Swelling
Erythema

Question 14

What is the most common joint in first presentation of gout?

Answer 14

1st metatarsophalangeal (MTP)
~70%
= Podagra

Question 15

Why are peripheral small joints in the lower extremities especially affected in gout?

Answer 15

Tissue temperature within them is physiologically lower, which promotes uric acid deposition.

Question 16

List 3 other commonly affected joints in gout

Answer 16

Ankle
Wrist
Knee

Question 17

What does chronic gouty arthritis lead to?

Answer 17

Tophi formation
Painless hard nodules with possible joint deformities
May appear yellow/ white because of overlying attenuated skin

Question 18

Where may bone tophi be seen?

Answer 18

Elbows
Knees
Extensor surfaces of forearms

Question 19

Where may soft tissue tophi be seen?

Answer 19

Pinna of external ear
Achilles tendon
Olecranon bursa

Question 20

What is the gold standard investigation for suspected gout?

Answer 20

Arthrocentesis + synovial fluid analysis

Question 21

What is seen on synovial fluid analysis in gout?

Answer 21

Needle shaped negatively birefringent monosodium urate crystals under polarised light

Question 22

When should uric acid be measured in gout? What result supports diagnosis?

Answer 22

Acutely: Uric acid >,360 umol/L

If <360, repeat once acute episode has settled (~2w later)

Question 23

Why must serum uric acid levels be interpreted with caution?

Answer 23

Not always raised in acute gouty arthritis

Question 24

List 4 radiological features of gout

Answer 24

Joint effusion (early)
Well-defined punched out erosions with sclerotic margins in a juxta-articular distribution
Eccentric erosions
Soft tissue tophi

Question 25

What are the punched-out lytic bone lesions in gout also known as?

Answer 25

Rat-bite erosions

Question 26

Describe first line management of acute gout

Answer 26

NSAID at max dose e.g. Naproxen continued until 1-2 days after attack resolved + PPI or Colchicine or Prednisolone 30-35mg OD for 5 days + Continue allopurinol if taking already

Question 27

What are 2 unfavourable features of colchicine use in acute gout?

Answer 27

Slower onset of action (than NSAIDs) SE: Diarrhoea

Question 28

How should colchicine be used in those with renal impairment?

Answer 28

Use with caution Reduce dose if eGFR is 10-50 ml/min Avoid if eGFR < 10 ml/min

Question 29

What is an alternate treatment of acute gout if colchicine and NSAIDs are contraindicated?

Answer 29

Intra-articular/ IM steroid injection

Question 30

In which patients should urate lowering therapy be offered?

Answer 30

All patients after their first attack of gout

Question 31

Give 5 indications where urate lowering therapy is particularly recommended

Answer 31

>,2 attacks in 12 months Tophi Renal disease Uric acid renal stones Prophylaxis if on cytotoxics/ diuretics

Question 32

When should urate lowering therapy be started?

Answer 32

Once inflammation has settled as ULT is better discussed when patient is not in pain

Question 33

Why should anti-inflammatories be given during acute gout and for at least 1w before ULT?

Answer 33

XOIs during acute flare may exacerbate Sx by mobilising urate crystals

Question 34

What is the first line agent in urate lowering therapy? What is the MOA?

Answer 34

Allopurinol 100mg OD with dose titrated every few weeks to aim for a serum uric acid of < 360 µmol/l Xanthine Oxidase inhibitor

Question 35

In which patients should the starting dose of allopurinol be reduced?

Answer 35

Reduced eGFR

Question 36

What additional drug should be considered alongside initiation of allopurinol?

Answer 36

Colchicine cover (NSAIDs if colchicine not tolerated) May need to be continued for 6 months

Question 37

What is the second line agent in urate lowering therapy? What is the MOA? When is this indicated?

Answer 37

Febuxostat Xanthine Oxidase inhibitor When allopurinol is not tolerated/ is ineffective

Question 38

Name a drug that can be used in refractory cases for urate lowering therapy

Answer 38

Pegloticase Uricase (Urate oxidase) enzyme that catalyses degradation of urate

Question 39

List 3 lifestyle modifications for management of gout

Answer 39

Reduce alcohol + avoid during acute attack Lose weight if obese Avoid food high in purines

Question 40

Which drug may be suitable for patients with gout and co-existing hypertension?

Answer 40

Losartan Has specific uricosuric action

Question 41

How does vitamin C intake affect serum uric acid levels?

Answer 41

Increased Vitamin C intake decreases uric acid levels