A 62-year-old man is diagnosed with chronic myeloid leukemia and is treated with intensive chemotherapy. He goes into remission, but develops pain in his left wrist. On physical examination, the wrist is warm with swelling. Fluid aspirated from the wrist joint is subjected to polarizing light microscopy and shows needle-shaped crystals with negative birefringence. Which of the following processes most likely was important in the pathogenesis of his wrist pain?