The presence of uric acid crystals is generally of little clinical significance. They are found in acidic urine (pH below 5.5). The formation of uric acid crystals can by caused by a combination of factors including a diet rich in meat, decreased urine volume or a condition that acidifies urine such as chronic diarrhea. They are also present in individuals who have gout or during chemotherapy.
In individuals with kidney stones, the repeated presence of uric acid crystals in the urine could indicate the probable nature of the stone (or the substance that it formed out of). It should be noted, however, that most patients with uric acid crystals will never form stones.