Urinary Crystals in Patients with and without Urolithiasis

Abstract

The present study was conducted to evaluate urinary crystals in patients with and without urinary calculi. Three hundred and twenty-two patients were enrolled retrospectively, including 219 stone-formers and 103 cases with non-calculus genitourinary tract diseases. The stones were analyzed with infrared spectrophotometer or scanning electron microscopy. Components of the stones included whewellite, weddelite, carbonated-apatite, struvite, brushite and uric acid. Various kinds of crystals were detected from urinalysis including calcium oxalate, amorphous phosphate, triple phosphate and uric acid in 83 patients (37.9%) of the urinary calculus group and 13 patients (12.6%) of the non-calculus group. Of the 83 cases, 75 (90.4%) showed that urinary crystals corresponded to the components of the urinary calculi. Calcium oxalate was the most common crystal in the urinalysis (44.4%). Concerning the pH values from urinalysis, the urine containing uric acid crystals had the lowest pH value (mean 5.30), and the triple phosphate crystals-containing urine had the highest pH value (mean 7.47). The study showed that approximately two-fifths of the patients with urinary calculi had crystals in urine, and there was good correlation between the urinary crystals and the components of the urinary calculi. Further, urinary crystals were found more frequently in patients with urinary calculus than in those without.