Crystal-Induced Arthropathies

Question 0

Enzyme involved in purine salvage

Answer 0

Hypoxanthine guanine phosphoribosyl transferase (HPRT)

Question 1

Rate-limiting enzyme for purine biosynthesis

Answer 1

Phosphoribosyl pyrophosphate (PRPP) synthase

Question 2

Renal function that is affected in “secondary underexcreters” of urate

Answer 2

Glomerular filtration

Question 3

Renal function that is affected in “primary underexcreters” of urate

Answer 3

Tubular secretion

Question 4

Diets high in this carbohydrate can increase serum urate, owing to a unique metabolic pathway

Answer 4

Fructose

Question 5

Diuretics that block urate excretion and cause hyperuricemia (2)

Answer 5

Thiazide and loop diuretics

Question 6

Weak acid drugs that block urate excretion and cause hyperuricemia (2)

Answer 6

Low-dose salicylates and nicotinic acid

Question 7

Anti-TB drugs that block urate excretion and cause hyperuricemia (2)

Answer 7

Isoniazid and pyrazinamide

Question 8

Drugs that inhibit the URAT-1 transporter and have modest urate-lowering effects

Answer 8

Losartan and high-dose salicylates

Question 9

Concentration of uric acid at which crystals may form

Answer 9

> 6.8 mg/dL (0.40 mmol/L)