Week 2.06 Part 2

Question 1

Uric acid is derived from:

Answer 1

Purines

Question 2

The predominant form of uric acid/urate in articulation fluid is:

Answer 2

Mono-sodium urate

Question 3

Consider Fig below showing that five biochemical steps are required in the conversion of AMP to uric acid. How many of these steps are catalyzed by xanthine oxidase?

Fig. 1. Breakdown pathways for adenosine 5’-monophosphate (AMP) and related nucleotides

Answer 3

Two

Question 4

Which of the following statements is, in general, true about the plasma uric acid/urate concentration?

Answer 4

It is around 80-100% of the solubility of urate in water

Question 5

A male patient with hyperuricemia and gouty arthritis was satisfactorily treated with allopurinol and then ceased medication. Which one of the following sequences of plasma urate levels (in the order: pre-treatment; during-treatment; post-treatment) would be expected:

Answer 5

0.42 mM; 0.34 mM; 0.44 mM

Question 6

Which one of the following act to lower plasma urate levels:

Answer 6

Enhanced conversion of hypoxanthine to IMP

Question 7

The Lesch Nyhan syndrome features hyperuricemia, gouty arthritis and various CNS manifestations including developmental delay. It arises, in part, from which one of the following of biochemical defects:

Answer 7

suppressed conversion of guanine to GMP

Question 8

Suicide inhibition of xanthine oxidase occurs during treatment for hyperuricemia with which one of the following:

Answer 8

allopurinol

Question 9

Which of the following is not a urate lowering drug?

Answer 9

Colchicine

Question 10

A 57 year old man reports that he has been taking his recommended dose of allopurinol (400mg daily) for the last 6 months but he has had 3 attacks of gout within the last 2 months, one of which was confirmed by the presence of urate crystals on synovial fluid analysis. He is on no other medication. He has small tophi at both olecranons but no joint inflammation. His current serum urate is 0.28mmol/L. The best option is to:

Answer 10

Add colchicine 0.5mg twice daily

Question 11

A 43 year old man with a second renal transplant has proven, non-tophaceous gout, with 6 attacks in the last year, 2 of which forced him to miss work. His transplant medications include azathioprine 50mg twice daily and prednisone 7mg daily. Because of his need to continue azathioprine, his renal physician has requested that allopurinol be avoided. His current blood/serum results are: creatinine 107µmol/L, urate 0.52mmol/L, ALT 31, AST 29. Which of the following would not be an acceptable option to help control his gout?

Answer 11

Febuxostat

Question 12

A 75 year old woman presents to emergency with a painful, swollen knee of 2 days duration. Aspiration of the joint fluid reveals: cell count 43.2 x 109/L; Gram stain negative; needle-shaped strongly negatively birefringent crystals; culture proceeding. She has hypertension, renal insufficiency (eGFR 27) and cardiac failure, all of which are under control on medications. What is the best approach?

Answer 12

Prednisone, initially 20mg daily

Question 13

Which of the following is true?

Answer 13

If an attack of gout occurred in the joint 6 weeks earlier, urate crystals will usually still be detectable in the synovial fluid

Question 14

Which of the following is not true in regard to severe allopurinol hypersensitivity syndrome?

Answer 14

The risk is higher if higher maintenance doses of allopurinol are used

Question 15

In regard to synovial fluid examination for crystals:

Answer 15

Betamethasone (Celestone Chronodose) crystals have the same properties of birefringence as monosodium urate monohydrate crystals

Question 16

Which of the following combinations is not appropriate for chronic gout?

Answer 16

Allopurinol and febuxostat