DMSA

Succimer (DMSA) is an oral chelating agent that binds heavy metals such as lead, arsenic, and mercury, forming water-soluble complexes excreted in urine. It is the preferred chelator for symptomatic or significantly elevated pediatric lead poisoning (especially when levels are too high for observation but patient is not encephalopathic), as it can be given orally and has a better safety profile than agents like EDTA or dimercaprol (BAL). Side effects include GI upset, elevated liver enzymes, and neutropenia; it should be used cautiously in renal impairment since it is renally excreted. In a different clinical use, Tc-99m DMSA is a radiopharmaceutical that binds to renal tubular cells and is used in nuclear scintigraphy to assess renal cortical morphology, commonly ordered in children with recurrent UTIs or suspected vesicoureteral reflux to detect pyelonephritis-related scarring or differential renal function. This dual usage (chelator vs. imaging tracer) is a classic board distinction point - the same abbreviation represents different clinical tools depending on context (toxicology vs. nephrology/radiology).