Heavy Metal Components in Blood and Urinary Stones of Urolithiasis Patients

Lifestyle, food intake, and exposure to chemicals are potential risk factors for the development of calcium urolithiasis. Pb, Cd, and Hg have been proved to cause renal illness, and urinary tract stones might be caused by exposure to metals. Therefore, this study aimed to measure the concentration of metals in urinary tract stones and blood simultaneously in urolithiasis patients. Moreover, we intended to determine whether urinary tract stones can be regarded as a biomarker of exposure or an effect marker in a population with environmental exposure to metals. Thirty-five urolithiasis patients (case) and 34 healthy inhabitants (control) were recruited in this study. The contents of Pb, Cd, Cr, Cu, Ni, As, Zn, and Hg were determined in urinary stones and blood in the case and control groups. The most abundant metals were Zn and Cu in blood and Zn and Ni in urinary stones. Significantly higher levels of Zn, Ni, and As were found in calcium phosphate stones than in calcium oxalate or uric acid stones. The majority of metals were not present at consistent levels in both blood and urinary stones, except for Zn. Urinary stones might be explained as providing another metabolic pathway for metal contamination. Moreover, as the metals with the highest content in urinary stones were Ni and Zn, and Ni content was very much higher than in other countries, contamination by Ni should be further taken into consideration if there is any serious contamination in Taiwan.