DMSA: Dimercaptosuccinic Acid
DMSA stands for Dimercaptosuccinic acid (also known as succimer or meso-2,3-dimercaptosuccinic acid). 1, 2
Two Distinct Clinical Applications
DMSA has two completely separate medical uses that should not be confused:
1. Nuclear Medicine Imaging Agent (Tc-99m DMSA)
Technetium-99m-labeled dimercaptosuccinic acid (Tc-99m DMSA) is a radiotracer used for renal cortical scintigraphy to evaluate kidney structure and function. 1
The compound undergoes cortical tubular binding in the kidneys, making it ideal for detecting renal parenchymal abnormalities, scarring, and calculating differential kidney function between the two kidneys. 1
This is the primary context in which DMSA appears in pediatric urology and nephrology guidelines, particularly for evaluating children with urinary tract infections, vesicoureteral reflux, and suspected pyelonephritis. 1, 3
The imaging agent provides superior sensitivity compared to ultrasound for detecting acute pyelonephritis and renal scarring in pediatric populations. 1, 3
2. Oral Chelating Agent (Succimer)
Oral dimercaptosuccinic acid (succimer) is a sulfhydryl-containing, water-soluble chelating agent used to treat heavy metal poisoning, particularly lead toxicity. 4, 5, 6
This formulation is administered orally at doses of 30 mg/kg/day to enhance urinary excretion of lead and other heavy metals including mercury, arsenic, and cadmium. 7
The chelating form has been in clinical use since the 1950s and is considered safer and more effective than older chelating agents for treating lead poisoning in children. 5, 6
Critical Distinction
These are two entirely different pharmaceutical preparations with different routes of administration, mechanisms of action, and clinical indications. The imaging agent (Tc-99m DMSA) is administered intravenously in trace amounts for diagnostic purposes, while the chelating agent (succimer) is given orally in therapeutic doses for treatment of metal poisoning. 1, 2, 7