What chelation regimen is appropriate for a child with a blood lead level of 75 μg/dL?

In cases of significant lead poisoning, particularly when a child's blood lead level reaches 75 μg/dL or higher, a more aggressive chelation therapy is required to effectively lower the lead burden in the body. The combination of dimercaprol and calcium disodium edetate (EDTA) is particularly effective in addressing high blood lead levels. Dimercaprol acts by forming stable complexes with lead, enhancing its excretion through the kidneys, while calcium disodium edetate facilitates the removal of lead from the body's tissues more efficiently.

Using both agents together allows for a synergistic effect that can more effectively mobilize lead from stored sites in the body and help to rapidly reduce blood lead levels. This combined approach is essential in preventing further neurological damage and other health complications associated with lead toxicity in children.

Other agents listed, such as succimer, are effective but are generally used in cases of moderate lead poisoning, whereas the critical situation presented with a blood lead level of 75 μg/dL necessitates the more intensive combination therapy to ensure an appropriate and quick response to the child's condition.