Which one of the listed conditions is not associated with elevated plasma uric acid concentration?

Which one of the listed conditions is not associated with elevated plasma uric acid concentration?

• A. Allopurinol overtreatment
• B. Gout
• C. Lesch-Nyhan syndrome
• D. Renal disease

Answer: (A)

The key concept is that plasma uric acid reflects the balance between how much uric acid is produced and how well it is excreted by the kidneys. Conditions that raise production or impair excretion tend to yield higher uric acid levels. Gout is a consequence of hyperuricemia, so elevated plasma uric acid is typical. Lesch-Nyhan syndrome causes excessive purine breakdown due to HGPRT deficiency, leading to marked overproduction of uric acid and high levels in the blood. Renal disease impairs uric acid excretion, also causing elevated plasma uric acid. In contrast, allopurinol inhibits xanthine oxidase, reducing uric acid production. Overtreatment with allopurinol lowers plasma uric acid rather than raising it (and can even cause hypouricemia and risk of xanthine stones). So the option that is not associated with elevated plasma uric acid is allopurinol overtreatment.

The key concept is that plasma uric acid reflects the balance between how much uric acid is produced and how well it is excreted by the kidneys. Conditions that raise production or impair excretion tend to yield higher uric acid levels. Gout is a consequence of hyperuricemia, so elevated plasma uric acid is typical. Lesch-Nyhan syndrome causes excessive purine breakdown due to HGPRT deficiency, leading to marked overproduction of uric acid and high levels in the blood. Renal disease impairs uric acid excretion, also causing elevated plasma uric acid. In contrast, allopurinol inhibits xanthine oxidase, reducing uric acid production. Overtreatment with allopurinol lowers plasma uric acid rather than raising it (and can even cause hypouricemia and risk of xanthine stones). So the option that is not associated with elevated plasma uric acid is allopurinol overtreatment.