[Detection of chronic lead poisoning. Value of the assay of erythrocyte protoporphyrin].

The most common screening tests for lead poisoning are reviewed. Stippled red cells are inconstant and appear too late. Blood lead concentrations are difficult to measure accurately and often are uncorrelated with body lead stores. Excess of delta aminolevulinic acid and coproporphyrin in urine does not appear early enough. A marked increase of erythrocyte protoporphyrin level practically clinches the diagnosis, later confirmed by increase of lead in urine after an EDTA lead-mobilization test. Measurements of erythrocyte protoporphyrin levels are easy to perform, more sensitive, more precocious and cheaper than the other methods, but their relative lack of specificity must be borne in mind.