Interrelation between urinary delta-aminolevulinic acid (ALA), serum ALA, and blood lead in workers exposed to lead

Using a fluorometric HPLC method, we determined delta-aminolevulinic acid (ALA) in sera and urine samples from 16 lead workers with blood lead levels ranging from 19 to 107 microG/100 ml. The concentration of ALA in serum correlated highly with the urinary ALA concentration (gamma = 0.957 for ALA mg/1; gamma = 0.967 for ALA mg/g creatinine). The ALA concentrations in the serum of lead workers ranged from 11 to 151 micrograms/1 with a mean of 51 micrograms/1. In addition, the concentrations of urinary ALA (mg/g creatinine) and serum ALA micrograms/1) had a strong correlation with blood lead concentrations (gamma = 0.838 and 0.892, respectively). These data indicate that the measurement of serum ALA, as well as urinary ALA, is very useful for the biological monitoring of occupational lead exposure.