Lead poisoning vs Mercury poisoning
How to tell Lead poisoning and Mercury poisoning apart when a board question makes them look alike.
Lead is abdominal pain plus heme-synthesis anemia/basophilic stippling; mercury is tremor, neuropsychiatric change, sensory loss, and exposure-specific toxicity.
Side by side
Lead poisoning causes abdominal pain, constipation, neurocognitive deficits, developmental delay, irritability, neuropathy, anemia, basophilic stippling, and Burton lines.
Mercury poisoning causes neuropsychiatric symptoms, tremor, ataxia, visual field constriction, paresthesias, erethism, gingivostomatitis, or acrodynia depending on form and exposure.
Lead inhibits ALA dehydratase and ferrochelatase, impairing heme synthesis and causing neurologic, GI, renal, and hematologic toxicity.
Mercury binds sulfhydryl groups and injures the nervous system and kidneys; methylmercury is especially neurotoxic.
Elevated blood lead level, microcytic anemia, basophilic stippling, high zinc protoporphyrin, old paint or battery exposure, and chelation response support lead poisoning.
Elevated mercury level, fish/industrial exposure, tremor, personality change, sensory disturbance, and renal findings support mercury poisoning.
The trap
Both can cause neurologic symptoms, so anemia/basophilic stippling and abdominal colic point to lead, while tremor/erethism and fish/industrial exposure point to mercury.
The repair move
For heavy metals, pair the exposure with the signature blood smear or neurologic pattern.
Try a free question
CoreA child in an older home has abdominal pain, constipation, irritability, developmental delay, microcytic anemia, and basophilic stippling. Which poisoning is most likely?
Show answer and explanation
Answer: A. Lead poisoning. Old-home exposure with abdominal pain, developmental delay, microcytic anemia, and basophilic stippling supports lead poisoning.
Why the other choices are tempting
- B. Mercury poisoning emphasizes tremor, ataxia, sensory changes, and neuropsychiatric symptoms.
- C. Arsenic poisoning causes GI symptoms, QT prolongation, neuropathy, and skin changes.
- D. Iron poisoning causes GI corrosive injury, shock, metabolic acidosis, and hepatic injury.
- E. Cyanide poisoning causes severe lactic acidosis and collapse.
Flashcards
Tap a card to flip it.
What enzymes does lead inhibit?
Lead inhibits ALA dehydratase and ferrochelatase.
What smear finding supports lead poisoning?
Basophilic stippling supports lead poisoning.
Quick answers
What is the fastest way to tell Lead poisoning from Mercury poisoning?
Lead is abdominal pain plus heme-synthesis anemia/basophilic stippling; mercury is tremor, neuropsychiatric change, sensory loss, and exposure-specific toxicity.
What is the key clue for Lead poisoning?
Lead poisoning causes abdominal pain, constipation, neurocognitive deficits, developmental delay, irritability, neuropathy, anemia, basophilic stippling, and Burton lines.
What is the key clue for Mercury poisoning?
Mercury poisoning causes neuropsychiatric symptoms, tremor, ataxia, visual field constriction, paresthesias, erethism, gingivostomatitis, or acrodynia depending on form and exposure.
What is the common trap with Lead poisoning vs Mercury poisoning?
Both can cause neurologic symptoms, so anemia/basophilic stippling and abdominal colic point to lead, while tremor/erethism and fish/industrial exposure point to mercury.