Gout and Crystal Arthritis

Question 1

What is the prevalence of gout in men in western dveloped countries?

Answer 1

3-6%

Question 2

What is the prevalence of gout in women in western developed countries?

Answer 2

1-2%

Question 3

What are the common comorbidities of gout?

Answer 3

obesity, HTN, CKD, diabetes

Question 4

What is the main risk factor for gout?

Answer 4

hyperuricaemia

Question 5

What defines hyperuricaemia?

Answer 5

serum urate > 0.405mmol/L

Question 6

How is urate made?

Answer 6

purine catabolism results in xanthine which is converted to urate by xanthine oxidase

Question 7

What causes primary urate overproduction?

Answer 7

accelerated purine synthesis (PRPP synthase enzyme hyperactivity)
impaired purine salvage (HGPRT1 deficiency)
hereditary defects of energy metabolism

Question 8

What causes secondary urate overproduction?

Answer 8

Autoimmune and haemolyticanaemias
Sickle cell disease
Polycythaemiavera
Ineffective erythropoiesis (megaloblastic anaemia, thalassemia)
Myeloproliferative and lymphoproliferative disorders
Tumourlysis syndrome

Question 9

What lifestyle factors cause urate overproduction?

Answer 9

diet and alcohol

Question 10

How is urate excreted?

Answer 10

GI (20-30%) and renal

Question 11

What causes primary underexcretion of urate?

Answer 11

Renal urate transporter mutations (ABCG2 loss of function and URAT1 gain of function)

Question 12

What causes secondary underexcretion of urate?

Answer 12

CKD, diuretics, aspirin, pyrazinamide, ciclosporin, lead

Question 13

What are the different clinical presentations of gout?

Answer 13

gout flares, subcutaneous tophi, chronic gouty arthritis

Question 14

Which is the most common joint in a gout flare?

Answer 14

MTP1

Question 15

What do you see on joint microscopy in gout?

Answer 15

intra-cellular needle-shaped negatively birefringent crystals

Question 16

What do you see on plain film in gout?

Answer 16

gouty bone erosions: evidence of cortical break, overhanging edge with sclerotic margin

Question 17

What is the management for a gout flare?

Answer 17

NSAIDs, high dose prednisolone, colchicine, steroid joint injection

Question 18

What is the mechanism of action of allopurinol?

Answer 18

xanthine oxidase inhibitor

Question 19

What is the mechanism of action of probenecid?

Answer 19

promotes urinary excretion of uric acid

Question 20

What is the dose regime for allopurinol?

Answer 20

commence at 100mg daily (50mg daily if renal failure) and uptitrate by 100mg every 2-4 weeks until reach <0.36mmol/L serum urate

Question 21

What is allopurinol hypersensitivity syndrome?

Answer 21

a reaction to allopurinol that results in desquamating rash, fever, eosinophilia, end organ damage

Question 22

Which gene is associated with allopurinol hypersensitivity syndrome?

Answer 22

HLA B*5801

Question 23

Which drugs interact with allopurinol?

Answer 23

azathioprine, mercaptopurine, theophylline, thiazide diuretics

Question 24

Which diseases are calcium pyrophosphatase deposition disease associated with?

Answer 24

hypomagnesaemia, hyperparathyroidism, haemochromatosis, hypophosphataemia, OA, joint injury