Low level kidney cadmium and effects on urinary alpha-1-microgloblin

摘要

Background: Cadmium (Cd) can cause renal damage after high-level exposure. Recently such effects have been shown also at low-level exposure, as measured by Cd in blood or urine. Using urinary Cd may, however, result in erroneous conclusions. Associations with Cd in kidney biopsies from a healthy population have not been examined previously. As cadmium damages the proximal tubular cells, the reabsorption of low-molecular-weight (LMW) proteins is decreased and results in increased urinary excretion. One of the most commonly used biomarkers linked to cadmium nephrotoxicity is the LMW protein alpha-1-microglobulin (A1M). Aims: The aim of this study was to explore the relation between kidney Cd and urinary excretion of alpha-1-microglobulin in kidney donors, representing the healthy part of the general population Methods: Cd was determined in kidney cortex biopsies from 109 living kidney donors. A1M and creatinine was analyzed in overnight and 24-hour urine samples. Correlations between single variables were assessed by Spearman correlation coefficients. Associations between urinary A1M and kidney Cd and background variables were assessed using multiple linear regression with backward elimination. Results: In spite of relatively low kidney Cd levels (median 13 μg/g, range 1.5-55 μg/g) kidney Cd and urinary A1M were positively associated, with significant correlations both in 24-hour and overnight samples. In multivariate analyses, there were significant associations between kidney Cd and creatinine-adjusted A1M in never-smokers, both in 24-hour and overnight urine, in a model including age, sex and weight. Conclusions: This study provides support for an association in the general population between kidney Cd levels and urinary excretion of A1M, a biomarker for kidney damage. The results further confirm the importance of preventing environmental pollution by cadmium.