Crystal Arthropathies (Gout)

Question 1

5 characteristic clinical feature of gout

Answer 1

1. hyperuricemia (underexcretion)
2. acute monoarticular arthritis of the big toe in particular
3. acute polyarticular arthritis
4. tophi and chronic arthritis
5. nephrolithiasis

Question 2

what is tophi

Answer 2

deposits of urate around peripheral joints (feer ankle knees elbow, anything subjected to stress)

Question 3

comorbidities and risk factors of gout. Also list medications.

Answer 3

Question 4

2 causes of primary gout

Answer 4

1. overproduction (10%)
2. under-excretion (90%)

Question 5

secondary causes of gout

Answer 5

1. overproduction due to lymphoproliferative disorders, hemolytic anemias, psoriasis. this is due to myelodysplasia or myeloproliferative disorder causing more purine production, needing to be broken down.
2. under-excretion due to chronic renal failure and hypithyroidism. Tubular poisins and sieases including lactic acid, ketones, drugs etc.

Question 7

outline the biochemistry of gout and the presence of uric acid

Answer 7

Of all the patients with hyperuricemia:
• 90 % don’t excrete enough uric acid renally.
• On a low purine diet for 3 to 5 days, uric acid excretion is < 600
mg/24 hours • On a normal purine diet for 3 to 5 days, uric acid excretion is <
800 mg/24 hours
• 10 % have excessive uric acid production and/or intake.
• Hyperuricemia can be classified as primary or
secondary.
there is a direct relationship between serum uric acid levels and the incidence of gout

Question 8

diagnosing gout

Answer 8

• diagnosis should never be based on serum uric acid level laone.
• the value of serume urate in an acute flare is poor with a lower sensitivity and specificity.

YOU MUST LOOK FOR URATE CRYSTALS

Question 9

negatively vs positively bifringen crystals

Answer 9

CPPD crystals on the left: positively bifringent, beucuse it is BLUE when parallel to the line of compensation. Also more rhomboid. This is pseudogout.

MSU crystals: negatively birefringent because it is yellow when parallel to the line. This is true gout.

Question 10

outline the scoring system for diagnosing gout without joint fluid analysis

Answer 10

with this table, gout has been confiremd in 80% of patients with a score over 8.

Question 11

specific radiological lesions seen on an xray of someone with gout

Answer 11

• rate bite lesions: large erosionds with overhanging edges… often cloudy due to overlying tophus.

A tophus (plural: tophi) happens when crystals of the compound known as sodium urate monohydrate, or uric acid, builds up around your joints. Tophi often look like swollen, bulbous growths on your joints just under your skin

Question 12

treatment of acute gout

Answer 12

goal is to exclude septic arthritis and suppress pain and inflammation

1. nsaids and coxibs plus maybe a PPI. Or colchicine or corticosteroid
2. review at 4-6 weeks and assess lifestyle factors, serum uraet, renal function and glucose

Question 13

treatment for chronic gout

Answer 13

for recurrent attacks, treat to serum urate under 360 mM/L, initiate uric-acid lowering treatment with allopurinol, feboxuostat or probenecid.

• lifestyle modification.

Question 14

T/F NSAIDS are first line gout treatment

Answer 14

false. cholchycine is now the first line.

Question 15

which genes make someone susciptible to an aversive allopurinol reaction?

Answer 15

HLA genes: HLAB58 -01. Mostly seen in asians. Instead of allopurinol, they should go on fluboxistat.

Question 16