Significant increase of urinary mucoprotein in environmental-cadmium-exposed Japanese subjects

Urinary mucoprotein (U-MP) was determined in 169 Japanese environmental-cadmium-exposed and 81 non-exposed subjects. Urinary total protein, albumin, beta 2-microglobulin (beta 2-MG), cadmium (Cd) and creatinine were also measured. Significant increases in U-MP and other proteins were found in the Cd-exposed subjects. Significant correlations between each protein were seen in the Cd-exposed and the total group of subjects. U-MP was highly correlated with urinary beta 2-MG and their correlation coefficient was the highest in the total group of subjects. beta 2-MG was the most sensitive indicator among them to detect Cd-induced renal dysfunction, although beta 2-MG is degraded in urine with a pH less than 5.5 U-MP is an acid-soluble protein. Therefore, U-MP is also available for studies on renal dysfunction caused by exposure to Cd, in conjunction with beta 2-MG.