Abstract

Lead is a prevalent environmental pollutant and the heavy metal most frequently associated with toxic effects in humans. This study aimed to evaluate changes in urinary lead excretion following intravenous Ca-DTPA administration. We retrospectively included all patients treated at a medical clinic between January 2023 and March 2025 for suspected symptoms associated with gadolinium exposure who underwent intravenous Ca-DTPA chelation and had both pre- and post-chelation 24 h urine testing for 20 heavy metals. Urinary lead excretion was summarized using mean, standard deviation, median, and interquartile range, and non-parametric testing was applied because values were not normally distributed. A total of 63 participants were included, of whom 37 were female, with a mean age of 48.6 ± 12.5 years, ranging from 15 to 78 years. Median urinary lead excretion increased from 0.283 µg/24 h (IQR, 0.183–0.421) before treatment to 3.22 µg/24 h (IQR, 1.87–5.28) afterward (p < 0.001), corresponding to a median 11.8-fold increase. Participants aged ≥50 years had a higher median fold increase than younger participants (14.0 vs. 9.8; p = 0.003). All participants had detectable urinary lead levels, and intravenous Ca-DTPA administration was associated with a significant increase in urinary lead excretion. Older participants demonstrated greater lead mobilization and excretion than younger participants. These findings suggest that Ca-DTPA may reveal a mobilizable body burden of lead under the tested conditions, but they do not establish lead poisoning, reduction in total-body lead burden, symptom improvement, or long-term clinical benefit.

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