Question

Case 3:

A 47-year old man presents with severe pain in his right great toe. He is unable to bear weight on his right foot and there was no apparent trauma. He reports the pain started last night and continued to increase in severity. Based on his physical exam and laboratory findings he is diagnosed with gout. Gout can be caused by several different mechanisms and blood samples are drawn and urinalysis is performed. The results from this individual are listed below.

Patient Plasma Urate (mg/100 ml), Urinary Uric Acid (mg/24 hr)

Normal < 7.0, 413 ± 78

Patient 10.5, 215

What is the best explanation for the presentation of gout in this individual and please explain why the other choices are not consistent with the data or what additional information you may need to decide the root cause?

1. overproduction of purines

2. decreased salvage of purines

3. decreased urinary excretion of uric acid

After further discussion with the patient, he tells you that he recently switched from diet soda to regular soda because he read that the ‘fake sugar’ diet soda was bad for him; he tells you he drinks between 4 and 5 L of soda a day. (NOTE: The primary sugar in most sodas is fructose or high fructose corn syrup.) What is the potential impact of this dietary modification on the presentation of gout?

Answer 1

a. Ans: 3) Decreased urinary excretion of uric acid.

Explanation: From the above data, you can find that patient has less uric acid in urine and plasma level of urate is high. Other choices are not consistent. Because, you can not assume the production rate of purine or salvage pathway from the data given.

b. Fructose metabolism produces uric acid. Fructose also inhibits uric acid excretion, by competing with uric acid for accession of the transport protein SLC2A9. That's why dietary modification has been made.