A 65-year-old man with a history of hypertension presents with acute, severe monoarthritis of the first metatarsophalangeal joint (podagra), fever, and joint aspiration showing negatively birefringent, needle-shaped crystals under polarized light. Which metabolic abnormality most commonly underlies this condition?
- A Decreased renal excretion of uric acid ✓
- B Increased production of uric acid due to HGPRT deficiency
- C Increased calcium pyrophosphate deposition
- D Overproduction of uric acid due to dietary purines alone
Correct answer: A. Decreased renal excretion of uric acid
Explanation
Gout results from hyperuricemia; in approximately 90% of cases, the underlying mechanism is underexcretion of uric acid by the kidneys rather than overproduction. Thiazide and loop diuretics (commonly used for hypertension) decrease renal uric acid excretion and are a classic precipitant of gout. HGPRT deficiency (Lesch-Nyhan syndrome) causes overproduction and accounts for a minority of cases. Calcium pyrophosphate crystals are positively birefringent and cause pseudogout.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.