Erythrocyte pyrimidine-5'-nucleotidase activity as a sensitive indicator of lead exposure

Since the red cell enzyme pyrimidine-5'-nucleotidase (PN) is inhibited by lead, we examined the feasibility of using the activity of this enzyme as a measure of lead exposure. Erythrocyte PN activity was measured in 110 blood samples obtained from subjects working in industries which utilize lead and 40 control subjects. The measurements were then compared with a number of traditional indices of lead poisoning. These included blood and urine lead concentrations and free erythrocyte protoporphyrin, erythrocyte zinc protoporphyrin, urinary coproporphyrin and urinary delta-aminolaevulinic acid levels. There was a highly significant negative correlation between erythrocyte PN activity and blood lead concentration (-0,83; P less than 0,0001), which was greater than that for any of the other measurements. It was therefore concluded that erythrocyte PN activity is an excellent indicator of lead exposure.