Erythrocyte ALA-d activity in experimentally lead-poisoned ducks and its change during treatment with disodium calcium EDTA.

To determine useful procedures for the diagnosis and prognosis of lead poisoning in waterfowl caused by ingestion of lead pellets, erythrocyte delta-aminolevulinic acid dehydratase (ALA-d) was investigated in experimentally lead-poisoned ducks. A highly positive correlation was observed between the concentration of blood lead and the ALA-d activity ratio (the ratio of activated:non-activated enzyme activity) in those birds given seven lead pellets (3 mm diameter). The ALA-d activity ratio rapidly increased after the administration of lead pellets, but began to fall immediately after the initiation of disodium calcium ethylenediamine tetra-acetate (CaEDTA) therapy which resulted in a rapid decrease in the concentration of lead in the blood of these birds. In contrast, the ALA-d activity remained inhibited even after blood lead levels began to decrease following treatment. These results demonstrated that the ALA-d activity ratio is a very useful and sensitive indicator for the diagnosis and evaluation of therapeutic effects after lead poisoning in waterfowl.