A randomized trial of calcium supplementation for childhood lead poisoning

Objective. Lead (Pb) poisoning remains a common disease among children despite successful public health efforts that have reduced its prevalence. Treatment options for children with blood Pb levels (BPbs) <45 mu g/dL are limited because chelation therapy is generally not indicated. Calcium (Ca) and Pb interactions are well documented. Competition for binding to Ca-binding proteins may underlie a mechanism for Pb absorption. The purpose of this study was to determine the role, if any, of supplemental Ca at reducing BPbs in moderately poisoned children. Methods. Children aged 1 to 6 years with BPbs 10 to <45 mug/dL were enrolled in a double-blinded, placebo-controlled trial of the effects of Ca supplementation on BPbs. Children received either a Ca-containing liquid or an indistinguishable placebo. Dosage was adjusted biweekly on the basis of responses to a dietary Ca intake questionnaire to reach 1800 mg in the Ca-supplemented group. Samples for BPbs and measures to assess safety were collected before and after 3 months of supplementation and after an additional 3 months of follow-up. Bivariate and multiple regression analyses were performed. Results. A total of 67 of 88 enrolled children with a mean age of 3.6 years completed 3 months of supplementation. There were no statistically significant differences between groups on hematologic and biochemical measures, including serum and urinary Ca, at any time points. The average compliance rate was estimated to be 80% for each group during the 3-month supplementation period. Conclusions. At enrollment, the average daily Ca intake in this group of inner-city children was greater than the recommended daily intake for age. Although BPbs declined during a 3-month period in both groups, Ca supplementation aimed at providing 1800 mg of Ca/day had no effect on the change in BPbs. Ca supplementation should not be routinely prescribed for mild to moderately Pb-poisoned children who are dietarily Ca sufficient.