Evaluation of a new specific analysis of urinary delta-aminolevulinic acid in man

A new specific method for urinary delta-aminolevulinic acid (ALA-U) measurement in man as a serial screening method for health control in occupational lead exposure was compared with a recommended, selective test (DAVIS method). The new test can be run fully automated, and the cost of material per sample is much lower than in the DAVIS method. ALA values obtained with this specific method were lower than those measured with the DAVIS method (= DAVIS values) in each case due to the elimination of interfering urinary compounds. In DAVIS values below the biological tolerance level (BAT-level) of 15 mg/l, the percentage of interfering compounds varied between 10 and 80%; above BAT level, these components represented about 20% of the total amount of ALA-U. A strong correlation can be demonstrated between specifically measured ALA values and the enzyme activity of ALA-dehydratase (ALA-D) in blood at lead levels (Pb-B) below 35 micrograms/dl (r = -0.768 for ALA-U/log ALA-D; n = 18).