Purine Metabolism and Gout

In gout, which enzyme deficiency leads to massive overproduction of uric acid and hyperuricemia due to inability to salvage hypoxanthine and guanine?

A 52-year-old man from Delhi presents with recurrent attacks of acute arthritis affecting the first metatarsophalangeal joint over the past 2 years. Serum uric acid is 8.2 mg/dL. Microscopy of synovial fluid shows needle-shaped, negatively birefringent crystals. What is the most common cause of hyperuricemia in this patient?

A 48-year-old man with a 5-year history of recurrent gout attacks is now being evaluated for chronic management. He has had 4 attacks in the past year despite lifestyle modifications. Serum uric acid is 7.8 mg/dL, and 24-hour urinary uric acid excretion is 450 mg/day (normal: 400–800 mg/day). Which investigation would best guide the choice between xanthine oxidase inhibitor versus uricosuric agent?

A 52-year-old man from Delhi presents with acute onset severe pain in the right big toe, swelling, and erythema for 2 days. He has a history of recurrent similar episodes over the past 3 years. Serum uric acid is elevated at 8.2 mg/dL. Which investigation is most appropriate to confirm the diagnosis of acute gout?

A 52-year-old man with a 10-year history of gout presents to the emergency department with acute left ankle pain, swelling, and erythema for 12 hours. Serum uric acid is 8.2 mg/dL. Synovial fluid analysis shows needle-shaped, negatively birefringent crystals. What is the most appropriate immediate management?