Lead Poisoning

Basics

Lead has multiple mechanisms of toxicity:
- Binds sulfhydryl groups and affects multiple enzymatic processes
- Resembles Ca²⁺ thereby interfering with Ca²⁺-dependent processes, such as cell signaling
- May have mutagenic potential and play a role in human carcinogenesis
Distribution:
- Up to 99% of lead is bound to erythrocytes after initial absorption
- Ultimately redistributed into bone:
  - 95% of total body lead in adults
  - 70% of total body lead in children
- High lead levels in the serum compromise the blood–brain barrier and result in lead entry into the CNS and neurotoxicity
Often coexists with iron deficiency; this allows for increased lead absorption in the gut
Impairs heme synthesis, leading to elevated free erythrocyte protoporphyrin (FEP); these complex with zinc, resulting in elevated zinc protoporphyrin (ZPP)
Levels correlate poorly with symptoms:
- Associated with drops in intelligence quotient (IQ) and increase in violent behavior

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