An assessment of sensitivity biomarkers for urinary cadmium burden
Yuting Li, Hongmei Wang, Jie Yu, Qiong Yan, Honggang Hu, Lishu Zhang, Tian Tian, Xiang-Lei Peng, Shuo Yang, Shen Ke
Abstract
Abstract Background Excess cadmium (Cd) intake poses a general risk to health and to the kidneys in particular. Among indices of renal dysfunction under Cd burden measures are the urinary N-acetyl-β-D-glucosidase (UNAG) and urinary β 2 -microglobulin (Uβ 2 -MG) enzymes. However, the end-pointed values and the Cd burden threshold remain controversial because the scopes fluctuate widely. Methods To ascertain the clinical benchmark dose of urinary Cd (UCd) burden for renal dysfunction, 1595 residents near a Cd site were surveyed. Urine was sampled and assayed. A benchmark dose low (BMDL) was obtained by fitting UCd levels and index levels. Results We found that over 50% of the subjects were suffering from Cd exposure as their UCd levels far exceeded the national standard threshold of 5.000 μg/g creatinine (cr). Further analysis indicated that Uβ 2 -MG was more sensitive than UNAG for renal dysfunction. The BMDL for UCd was estimated as 3.486 U/g cr (male, where U is unit of enzyme) and 2.998 U/g cr (female) for UNAG. The BMDL for Uβ 2 -MG, which is released into urine from glomerulus after Cd exposure, was found to be 2.506 μg/g cr (male, where μg is the unit of microglobulin) and 2.236 μg/g cr (female). Conclusions Uβ 2 -MG is recommended as the sensitivity index for renal dysfunction, with 2.2 μg/g cr as the threshold for clinical diagnosis. Our findings suggest that Uβ 2 -MG is the better biomarker for exposure to Cd.