Introduction and Objectives
The formation of the stones is a complicated process that results from combination of factors in which the main phenomenon is the supersaturation of some compounds in urine that might crystallize forming solid concretions. This process is affected by the lack of crystallization inhibitors, the presence of crystallization promoters and some morpho-anatomic factors. The presence and role of heavy metals in lithogenesis is debated and little definitive information has been presented linking the presence or absence of selected metals in the stones and urine to the pathogenesis of the disease. The goal of this pilot study was to investigate the distribution of heavy metals in stones and urine of stone formers in order to evaluate their possible role in lithogenesis.
Material and Methods
Material was collected from 116 patients treated due to symptomatic upper urinary tract lithiasis. Mean age was 54.4 years (min 19, max 80). Stones were obtained after PCNL, URSL, ureterolithotomy or nephrectomies. Each stone was analyzed together with urine from 24-hour sample for heavy metals determination. The specimens were mineralized in microwave oven ETHOS (Mileston, Connecticut, USA). The analysis was performed with atomic absorption spectrometer (ICP-OES) Optima 5300 DV (Perkin Elmer, Massachusetts, USA) according to Polish Standard PN-EN ISO 11885. Results were described in terms of mean, standard deviation, median and 25th–75th percentile with W Shapiro-Wilk test. Correlation analysis was performed using Spearman's rang test. A value of p < 0.05 was considered significant.
Following parameters were statistically significant among analyzed:
- •strong negative correlation between the concentration of zinc in stones and the content of calcium oxalate,
- •strong positive correlation between the concentration of zinc in stones and the content of calcium phosphate and magnesium phosphate,
- •negative correlation between the concentration of chrome in stones and the content of magnesium phosphate,
- •negative link between the concentration of zinc, vanadium, molybdenum and copper in stones and the content of uric acid.
Strong correlations were also seen in following metallic elements analyzed in urine and stones:
- •positive link between the concentration of nickel, chromium, molybdenum, cobalt and vanadium both in urine and stones,
- •negative link in case of cadmium.
- 1.The preliminary results of our studies confirms the conclusions of other authors about the potential role of some metals as inhibitors or promoters of crystallization process in urinary tract. This deals with such an elements as zinc, copper and chromium.
- 2.In order to thoroughly evaluate the relationship between the distribution of particular heavy metals in urine and stones of stone formers further studies on larger group are needed.
- 3.The question about the role and influence of heavy metals elements on lithogenesis is still to be answered.
© 2009 European Association of Urology. Published by Elsevier Inc. All rights reserved.