]> 2026-07-31T07:51:37+00:00 WBR0900 0 en Uric acid The presentation of this patient is consistent with gouty arthritis. Hyperproduction or underexcretion of uric acid leads to hyperuricemia predisposing to gout. However, the crystal deposits in gouty arthritis are monosodium urate. Monosodium urate The presentation of this patient is consistent with gouty arthritis, a condition characterized by deposition of monosodium urate crystals. Calcium pyrophosphate dehydrate Calcium pyrophosphate dihydrate (CPPD) has a similar presentation to gout but it is caused by the accumulation of crystals of calcium pyrophosphate dihydrate in the connective tissues. Pseudogout usually involves larger joints than gout. The presence of rhombus-shaped crystals which are weakly birefringent on polarized light microscopy is diagnostic for pseudogout. Phosphoribosylpyrophosphate Increased levels of phosphpribosylpyrophosphate (PRPP) leads to the overproduction and accumulation of uric acid leading to hyperuricemia and hyperuricosuria. Increased levels of PRPP are present in Lesch-Nyhan Syndrome. Decreased levels of hypoxanthine guanine phosphoribosyl transferase (HGPRT) causes this accumulation, as PRPP is a substrate used by HGPRT during purine salvage. Calcium The presentation of this patient is consistent with gouty arthritis. Gout is not characterized by calcium deposition in the joint. Pathophysiology A 63-year-old obese man with history of hypertension treated with thiazide diuretics complains of rapidly progressive pain in his big toe. The pain began in the morning and has become much worse in the last 6 hours. On physical exam, the toe is erythematous, swollen and tender to palpation. The patient reports two similar prior episodes that were less painful and resolved spontaneously. Synovial analysis reveals strongly birefringent needle-shaped crystals on polarized light microscopy. Deposition of which of the following most likely explains the symptoms in the patient? B Musculoskeletal/Rheumatology 2020-10-28T02:01:52Z 2459150.5846296 WBR0900