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Effects of iron deficiency on lead excretion in children with moderate lead intoxication
M E Markowitz1, J F Rosen, P E Bijur
1Department of Pediatrics, Albert Einstein College of Medicine, Montefiore Medical Center, Bronx, New York 10467.
Insights
Iron status impacts calcium disodium edetate (CaNa2EDTA)-induced lead diuresis in children. Higher serum ferritin levels showed a small but significant increase in urinary lead excretion, potentially affecting chelation therapy decisions.
Area of Science:
- Pediatric Toxicology
- Environmental Health
- Clinical Chemistry
Background:
- Lead intoxication in children poses significant health risks.
- Chelation therapy, using agents like calcium disodium edetate (CaNa2EDTA), is a common treatment.
- The influence of nutritional status, specifically iron, on chelation efficacy is not fully understood.
Purpose of the Study:
- To investigate the effect of iron status on lead excretion following CaNa2EDTA chelation in children.
- To determine if serum ferritin levels correlate with urinary lead output during provocative testing.
Main Methods:
- 112 children with moderate lead intoxication underwent provocative testing with CaNa2EDTA.
- Blood samples were analyzed for lead, erythrocyte protoporphyrin, and serum ferritin.
- Urinary lead levels were measured over an 8-hour period post-administration.
Main Results:
- Blood lead and serum ferritin levels were significantly correlated with urinary lead excretion (r=0.542 and r=0.298, respectively; p<0.01).
- Serum ferritin independently predicted urinary lead excretion, with a 2.4 microgram increase in urinary lead for every 1 ng/ml rise in ferritin.
- In discriminant analysis, serum ferritin improved the accuracy of predicting provocative test outcomes by only 3% compared to blood lead levels alone.
Conclusions:
- Iron status, indicated by serum ferritin, has a small but statistically significant effect on CaNa2EDTA-induced lead diuresis in children.
- This finding may influence the interpretation of borderline provocative test results for chelation therapy.
- Iron repletion should be considered, and lead stores reassessed post-treatment for iron deficiency.
Abstract:
The effect of iron status on calcium disodium edetate (CaNa2EDTA)-induced lead diuresis was examined in 112 children with moderate lead intoxication. Patients whose blood lead levels were between 25 and 55 micrograms/dl and who had erythrocyte protoporphyrin concentrations greater than or equal to 35 micrograms/dl underwent provocative testing to determine the need for a full course of chelation therapy. A blood sample for lead, erythrocyte protoporphyrin, and serum ferritin determinations was obtained immediately before the intramuscular administration of CaNa2EDTA, 500 mg/m2. Determination of urinary lead level was based on an 8-hour urine collection. Blood lead and ferritin levels were significantly correlated with urinary lead excretion: r = 0.542 and 0.298, respectively, p less than 0.01 for both. Multiple regression models were tested to assess the independent effects of the variables. With blood lead level controlled, ferritin remained significantly associated with urinary lead excretion; for every 1 ng/ml increase in ferritin, urinary lead increased by 2.4 micrograms. This small effect of ferritin on urinary lead was illustrated in a discriminant analysis. Using blood lead level by itself as the independent variable resulted in a 76% correct assignment of provocative test outcomes. Knowing the ferritin level improved this assignment accuracy by only 3%. We conclude that the iron status, as measured by serum ferritin, of children with moderate lead intoxication, has a small but significant effect on CaNa2EDTA-induced lead diuresis. This effect may influence the interpretation of borderline provocative test outcomes. Although chelation therapy should not be withheld pending treatment of iron deficiency, lead stores should be reassessed after iron repletion.