The value of mobilization of lead by ethylenediamine-tetra-acetate in the diagnosis of lead poisoning

Abstract

Traditional laboratory tests for lead poisoning tend to fail in cases where a considerable interval has elapsed since exposure. We have used calcium ethylene-diamine-tetra-acetate (CaNa₂EDTA) for the quantitative mobilization of lead for diagnostic purposes.

In a control group of 50 individuals who had never worked with lead it was found that the average urinary excretion of lead in 24 hours amounted to 0·031 to 0·043 mg. The maximum value did not exceed 0·100 mg. After intravenous injection of CaNa₂EDTA the amount of excreted lead rose considerably, but did not exceed 0·350 mg./24 hr.

In a group of 47 individuals who had formerly worked with lead or who were still engaged in this work but did not show any symptoms of poisoning, the urinary lead levels before injection were higher than in the control group. After injection of CaNa₂EDTA the lead excretion in 24 hours increased considerably. After injection of CaNa₂EDTA, patients suffering from chronic lead poisoning showed a considerable increase of urinary lead excretion, which attained the order of milligrams in 24 hours.

The fractionated examination of the urine of 10 unexposed individuals, undertaken at intervals of three hours, showed after injection of CaNa₂EDTA no higher lead concentration than 0·500 mg./litre, the highest concentrations being observed six hours after injection. In the urine of individuals exposed to lead or suffering from lead poisoning a higher urinary lead concentration was found than in the control group, and the maximum was in these cases found at various time intervals.

It is concluded that the mobilization of lead may be of considerable value in the diagnosis of atypical cases of chronic lead poisoning, but the results can be evaluated only in association with the general clinical picture.