EFFECT OF ORAL PROTEIN LOAD ON URINARY PROTEIN EXCRETION IN WORKERS EXPOSED TO CADMIUM AND TO LEAD

An acute oral protein load causes a transient hyperfiltration that mig ht reveal a loss of glomerular permselectivity properties. The effect of an oral protein load on the urinary excretion rate of albumin (UAE) , beta-2-microglobulin (UB2MGE), and retinol-binding protein (URBPE) w as thus examined in cadmium- and lead-exposed workers. The results sho w a transient increase in UB2MGE and URBPE without relevant changes in UAE. These changes were also observed in control groups and are due t o competitive inhibition of tubular protein reabsorption by absorbed c ationic amino acids. These results do not support the hypothesis that the acute protein load test is of great utility in revealing a silent glomerular filtration disturbance in lead- or cadmium-exposed workers. However, it might disclose imminent renal tubular dysfunction in cadm ium workers not yet showing increased microproteinuria under baseline conditions. (C) 1996 Wiley-Liss, Inc.