The proteinuria of industrial lead intoxication

Studies of protein excretion were undertaken in seven males, aged 35-42 years, who had more than 5 years exposure to industrial lead and had clinically established Pb intoxication. Heavy metal intoxication with Cd and Hg causes proximal tubular abnormalities, i.e., aminoaciduria, glycosuria, phosphaturia. Similar abnormalities occur in Pb intoxication except that the nature of the proteinuria remains controversial. Studies of urinary proteins included 24-hr urine protein excretion, dextran gel separations, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), and beta 2 microglobulin (B2M) measurements. Creatinine clearances, and serum B2M concentrations were normal. Urine total protein distribution by SDS-PAGE and the B2M excretion rate were also normal. These data imply that the nephrotoxicity of Cd and Hg are different than that of Pb. We speculate on what might account for this difference. This study suggests that when examining a population exposed to Pb, the finding of tubular proteinuria should alert investigators to search for the presence of other toxic agents.