RESUMEN
Blood samples were collected from 113 subjects (56 males and 57 females) living in the district of Alfenas, in southern Minas Gerais state, Brazil, to establish reference values for delta-aminolevulinic acid dehydratase activity (ALA-D, EC 4.2.1.24). The state of health of the population was confirmed by hematological and biochemical parameters analyzed in blood and urine samples. ALA-D determination was performed according to the Berlin & Schaller spectrophotometric method. Distribution may be regarded as according to normal distribution and reference values obtained, in micromol x min(-1) x L(-1) erythrocytes, were: mean (+/- SD) = 54.5 (+/- 9.8); 95% confidence interval = 52.7-56.4; lower reference value (mean-2 SD) = 34.9. Mean ALA-D activity was higher than any other published elsewhere and the reference values established are useful as a baseline for evaluating ALA-D activity when monitoring persons exposed to lead. Age, gender, drinking, or smoking did not significantly alter (Student t-test, p < or = 0.05) the reference values for ALA-D.