Definition and Characteristics
Excessive urinary uric acid excretion secondary to either iatrogenic overproduction or increased renal clearance. Excretion rates of over 800 mg (4.8 mmol) per day in men and 750 mg (4.5 mmol) per day in women are considered abnormal.
Using the above definition, 7–12% of adults in the United States have hyperuricosuria. Amongst kidney stone formers, 20–30% have hyperuricosuria.
Molecular and Systemic Pathophysiology
Uric acid is produced in the liver and intestinal mucosa as the end product of purine nucleotide degradation. Both endogenous and dietary purines contribute significantly to daily uric acid production. Approximately one third of the uric acid load is secreted into the gastrointestinal tract and degraded by bacteria. The kidneys account for the remainder of uric acid excretion. Uric acid is freely filtered at the glomerulus and then both secreted and reabsorbed in the proximal tubule. The...