in workers chronically exposed to cadmium and without signs of renal insufficiency , plasma proteins with molecular weight ranging from 11,800 to 450,000 are excreted in greater amount in urine . 
 increased urinary excretion of low and high molecular weight proteins can occur independently . because of its greater stability in urine and provided a sensitive immunological technique is used , the determination of retinol - binding protein is a more practical and reliable test of proximal tubular function than beta 2-microglobulin . 
 the evaluation of renal function of workers removed from cadmium exposure indicates that cadmium - induced renal lesions , albeit of slow progression , are not reversible when exposures ceases . in workers chronically exposed to cadmium or removed from cadmium exposure , metallothionein in urine 
 is directly correlated with cadmium in urine but not with cadmium in blood or years of cadmium exposure . 
 the association between cadmium in urine and metallothionein in urine is independent of the status of renal function and the intensity of current exposure to cadmium . whereas the repeated ip injection of high doses of cadmium to rat gives rise to a mixed or tubular type proteinuria , the prolonged oral administration of cadmium results mainly in the development of a glomerular type proteinuria . 
 the former is usually reversible after cessation of treatment whereas the latter is not . 
 circulating antiglomerular basement membrane antibodies have been found in man and in rat chronically exposed to cadmium . 
 the pathogenic significance of this finding deserves further investigation.imagesfigure 5 .