username456789

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In Path we learned that the epiphyseal lines/hyperdensities seen in long bones with lead poisoning was actually due to increased CALCIUM deposits (but I don't recall the specific interactions with lead that cause it).

RR Path explains them as actual LEAD deposits.

Anyone have an idea what it really is?
 

Scylin

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I'd love to know the answer to this too. In my path class we were taught that the lead competes w/ calcium for binding to phosphate in bone (and I perhaps incorrectly assumed that it was the lead that caused the dense lead lines).

However, upon doing a bit more research I came across this explanation:

"The result of osseous lead poisoning effectively illustrates a specific example of how the dense metaphyseal band sign is formed. With lead toxicity, or plumbism, the lead ions deposit on the hydroxyapatite crystal but preferentially in the zone of provisional calcification. Lead inhibits osteoclastic remodeling, but it has no effect on osteoblasts. The result is an increase in the thickness and number of trabeculae at the metaphysis (2). The lead itself contributes very little to the metaphyseal density in plumbism. Whenever growing bone recovers from any pathologic insult or becomes lead poisoned, exuberant calcium deposition in the zone of provisional calcification yields dense metaphyseal bands."


Raber, Scott A. "The Dense Metaphyseal Band". Radiology, June 1999, 211:773-774

http://radiology.rsna.org/content/211/3/773.full#content-block


I'd be very interested to hear from others on this subject. :)
 

Rabbit Hole

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In Path we learned that the epiphyseal lines/hyperdensities seen in long bones with lead poisoning was actually due to increased CALCIUM deposits (but I don't recall the specific interactions with lead that cause it).

RR Path explains them as actual LEAD deposits.

Anyone have an idea what it really is?
In chronic lead poisoning, the increased density in long bones is primarily due to calcium deposits. Lead is deposited to a lesser degree. So the densities you see on x-ray is mostly calcium.

Imagine how much lead a person would have to eat in order for their bones to be replaced by actual lead. They would be dead before all that lead could be deposited.
 

Rabbit Hole

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Oh yea.. just to be clear, I think the term "lead lines" is used to describe the changes seen in gingiva/gums in a person with lead poisoning.
 

MilkmanAl

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Oh yea.. just to be clear, I think the term "lead lines" is used to describe the changes seen in gingiva/gums in a person with lead poisoning.
That's what I took from it, too.
 

username456789

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Oh yea.. just to be clear, I think the term "lead lines" is used to describe the changes seen in gingiva/gums in a person with lead poisoning.
They used it specifically referring to the deposits in the bones in our path class, but what do they know.
 

Rabbit Hole

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They used it specifically referring to the deposits in the bones in our path class, but what do they know.
I did a little googling and I think we are both correct about this "lead line" business. Apparently it's not a specific term.

Anyway, I think I found the answer to your question from the CDC website:

[FONT=verdana,arial,helvetica]RADIOLOGICAL EXAMINATION OF THE LONG BONES
X-rays of the long bones are unreliable for diagnosing acute lead poisoning, and they should not be obtained on a routine basis. They may provide some indication of whether lead poisoning has occurred in the past or has been ongoing for a length of time, and this may occasionally be important. Lines of increased density in the metaphyseal plate of the distal femur, proximal tibia, and fibula may be caused by lead which has disrupted the metabolism of bone matrix. Although these lines are sometimes called lead lines, they are areas of increased mineralization or calcification and not x-ray shadows of deposited lead.
.
 

Rabbit Hole

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I'm going a bit overboard with this.. but what the hell.

This explanation was more helpful from a radiology website: The Dense Metaphyseal Band Sign

Normal metaphyseal endochondral bone growth (in the zone of provisional calcification) requires the maintenance of a delicate balance between osteoblastic bone deposition and osteoclastic bone remodeling (1). Whenever growing bone is subjected to toxic, metabolic, neoplastic, or infectious stressors, proper osteogenesis is compromised. Stress on growing bone leads to poor endochondral bone formation. In general, when the stress is eliminated, rapid deposition of new bone at the metaphysis produces dense bands.

The result of osseous lead poisoning effectively illustrates a specific example of how the dense metaphyseal band sign is formed. With lead toxicity, or plumbism, the lead ions deposit on the hydroxyapatite crystal but preferentially in the zone of provisional calcification. Lead inhibits osteoclastic remodeling, but it has no effect on osteoblasts. The result is an increase in the thickness and number of trabeculae at the metaphysis (2). The lead itself contributes very little to the metaphyseal density in plumbism. Whenever growing bone recovers from any pathologic insult or becomes lead poisoned, exuberant calcium deposition in the zone of provisional calcification yields dense metaphyseal bands.