Characterization of the proteinuria in cadmium-exposed workers

Abstract

The concentration of several protein (β2-microglobulin, orosomucoid, albumin, transferrin) and of total amino acids was determined in the urine of 18 cadmium-exposed workers and in a group of matched nonexposed workers. The results were compared with the electrophoretic pattern of urinary proteins on agarose gel. Ten of the cadmium-exposed workers had an abnormal electrophoretic pattern, eight of them excreted larger quantities of high and low molecular weight proteins, and the other two showed only an increased excretion of high molecular weight proteins. An increased β2-microglobulin excretion was found in five workers with a normal urinary protein electrophoresis whereas only the urine of three exposed workers were found to be normal. We have confirmed a previous observation that in the majority of the cadmium-exposed workers with an abnormal electrophoretic pattern or an increased total proteinuria, not only low molecular weight proteins (β2-microglobulin) are excreted in greater amount but also high molecular weight proteins such as albumin and transferrin. Furthermore, in cadmium-exposed workers proteinuria is more closely related to the concentrations of albumin and orosomucoid in urine than that of β2-microglobulin. The change in urinary concentration of total amino acids was less marked than that of protein. The determination of both low and high molecular weight proteins ought to be recommended for detecting renal damage due to cadmium.