Lead, zinc and copper decorporation during calcium disodium ethylenediamine tetraacetate treatment of lead-poisoned children.

Asymptomatic Pb poisoning of children remains a serious public health problem in the United States. Ca disodium EDTA is often used therapeutically to reduce the body burden of Pb. Although this chelating agent promotes increased urinary excretion of Pb and lowers blood Pb concentration, it is a nonspecific metal chelator and it promotes a substantial increase in the urinary loss of the essential metal, Zn. In the work described here, the pattern and extent of changes in blood Pb and plasma Zn and Cu concentrations and of the urinary loss of these metals have been characterized in Pb-poisoned children receiving 5-day courses of 1000 mg of Ca disodium EDTA per m2 of surface area per day, given i.m. Both blood Pb and plasma Zn concentrations were reduced rapidly during treatment; plasma Cu concentration was unaffected. At 60 hr after the cessation of Ca disodium EDTA treatment, plasma Zn concentration rebounded rapidly to its pretreatment value but blood Pb concentration remained at about 60% of its pretreatment value. Treatment with Ca disodium EDTA produced an approximate 21-fold increase in the daily rate of urinary loss of Pb and about a 17-fold increase in the daily rate of Zn loss in urine. There was no increase in urinary loss of Cu above the endogenous level. The chelatable body burden of Pb was estimated by two related methods. Statistically significant correlations were found between chelatable Pb burdens estimated by either method and blood Pb concentrations before Ca disodium EDTA treatment. In contrast, no correlation was found between plasma Zn concentration and the urinary loss of Zn during chelation therapy.(ABSTRACT TRUNCATED AT 250 WORDS)