Chempath 1: Hyperuricaemia and gout

Question 1

Name the classical sign when Gout affects the 1st metatarsophalangeal joint ?

Answer 1

Podagra

Question 2

Describe the shape of Urate crystals in gout ?

Answer 2

Needle

Question 3

Describe the shape of Calcium pyrophosphate crystals in Pseudo gout?

Answer 3

Rhomboid

Question 4

Are gout crystals negatively or positively birefringent in polarised light ?

Answer 4

Negatively (blue at 90%)

Question 5

Are Pseudogout crystals negatively or positively birefringent in polarised light ?

Answer 5

Positively (blue at axis of red compensator)

Question 6

What is the acute treatment for gout ?

Answer 6

Colchicine

Question 7

What is the long term treatment for gout ?

Answer 7

Allopurinol

Question 8

Which anti-diuretics can precipitate gout attacks ?

Answer 8

Thiazide diuretics

Question 9

List 3 precipitants for gout attacks ?

Answer 9

Alcohol
Thiazide diuretics
Chemotherapy

Question 10

Which enzyme is the rate limiting step in de novo purine metabolism ?

Answer 10

PAT

Question 11

In which body tissue does the de Novo pathway predominate as the main pathway for purine synthesis ?

Answer 11

Bone marrow

High requirement for purines in bone marrow, so uses the De Novo pathway even though it is less efficient

Question 12

List some of the features of Lesch-Nyhan syndrome ?

Answer 12

• Inborn error of purine metabolism
• HGPRT deficiency means they cant use salvage pathway
• X-linked disease
• Gout in child
• Choreiform movements
• Mental retardation
• self mutilation (biting thumb/lip very hard)

less inhibition feedback to PAT - de novo pathway in overdrive - high IMP and high urate

Question 13

Which enzyme is the rate limiting step in the salvage pathway?

Answer 13

-HGPRT

Question 14

List 4 causes of decreased Urate excretion ?

Answer 14

• Lead poisoning
• Thiazide diuretics
• Barterr’s syndrome
• Aspirin

(renal failure)

Question 15

Which drug must never be given with Allopurinol ?

Answer 15

Azathioprine

causes increased bone marrow toxicity

Question 16

list the purines

Answer 16

A, G, I

Question 17

how are purines metabolised

Answer 17

purines - hypoxanthine - (XO) xanthine - (XO) urate - (uricase) allantoin (only in cows)

Question 18

when are MSU plasma concentrations higher

Answer 18

acidic and colder = less soluble

Question 19

describe de novo synthesis of purines

Answer 19

PAT = rate limiting
AMP and GMP = negatively regulate activity of PAT
PPRP +ve FB on PAT

Question 20

describe salvage synthesis of purines

Answer 20

main, recycling

HPRT = main enzyme

Question 21

features of gout

Answer 21

MSU crystals
inflammation in joint synovium
podagra (A), tophaceous (C)

Question 22

describe treatment for gout

Answer 22

1 - reduce inflammation
- NSAIDs, cholchicine, glucocorticoids

2 - post attack

• manage hyperuricemia
• h20, stop diuretics, allopurinol(X inhibitor), probenecid (increases renal excretion)