Hyperuricemia is the presence of high levels of uric acid in the blood. It is caused either by accelated generation of uric acid through purine metabolism or by impaired excretion in the kidney.

Humans lack urate oxidase, an enzyme which degrades uric acid. Increased levels predispose for gout and (if very high) renal failure. Apart from normal variation (with a genetic component), tumor lysis syndrome produces extreme levels of uric acid, mainly leading to renal failure.