Urinary N-acetyl-beta-D-glucosaminidase activity in lead-exposed workers

The adverse effects of long-term exposure to lead dust on renal tubular functions were studied in 39 male and 7 female workers in a secondary lead refinery. Laboratory examinations showed low or moderate lead absorption levels. The N-acetyl-beta-D-glucosaminidase (NAG) activity in urine showed significant correlation with each of the lead exposure indices. NAG activity increased remarkably in lead workers with blood lead (PbB) above 80 micrograms 100g-1. Blood urea nitrogen (BUN) showed significant correlation with PbB and logarithmic urine delta-amino-levulinic acid (log(ALAU)), but not with urine lead (PbU) and logarithmic urine coproporphyrin (log(CPU)). All the other indices of renal function were almost within the normal range and showed no correlation with lead indices. This study suggests that moderate lead absorption may cause renal tubular impairment, and NAG can be one of the most sensitive indices for estimating renal dysfunction due to lead poisoning.