Is total urinary lead excretion by children during chelation predicted by optimally timed 24-hour urine aliquots?

Approaches to chelation therapy for children with lead poisoning are evolving. While various regimens are in place at our institution, all guidelines have historically recommended monitoring daily 24-hour urine collections for the first 5 days of chelation. In non-toilet trained children, this necessitates foley catheterization with its inherent risks and difficult maintenance. The ability to predict total urinary lead excretion from fewer than five 24-hour urine collections during pediatric lead chelation has not previously been reported. The objective of this study is to evaluate the optimal timing and minimum number of urine aliquots necessary to predict total lead excretion. Retrospective chart review of 67 children with blood lead levels greater than 40 mcg/dL who underwent chelation for lead toxicity at our center between March 1, 2003 and January 5, 2003. Data included demographics (predictors) and total 24-hr urine Pb concentrations on days 1-5 during chelation (outcome). Differences in urinary lead levels were evaluated using a mixed model for repeated measures which accounts for missing values. Most patients were male (66%) and African-American (90%). 25.4% had a history of prior chelation. The mean age was 3.2 years. Only race and treatment were significantly associated with urinary lead excretion during chelation. After controlling for race and treatment, there were no significant differences in urinary lead levels after Day 3. Delta urinary lead levels were (mcg/L): 131.8 (p