Lead poisoning

[gpac123]

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See FA P. 354 2011...

It says that in lead poisoning, protoporphyrin accumulates. However, the first step lead poisoning inhibits is ALA dehydratase step. Why wouldn't ALA build up? It seems like with lead poisoning, you can't get beyond that to reach the protoporphyrin.

 

[cetona]

See FA P. 354 2011...

It says that in lead poisoning, protoporphyrin accumulates. However, the first step lead poisoning inhibits is ALA dehydratase step. Why wouldn't ALA build up? It seems like with lead poisoning, you can't get beyond that to reach the protoporphyrin.

According to some other sources, ALA does also build up. I'm guessing some ALA builds up because it can't get by the ALA dehydratase step, but the ALA that does get by then builds up behind ferrochelatase and accumulates as protoporphyrin.

 

[lackli]

According to some other sources, ALA does also build up. I'm guessing some ALA builds up because it can't get by the ALA dehydratase step, but the ALA that does get by then builds up behind ferrochelatase and accumulates as protoporphyrin.

Another tidbit to add: ALA will build up because the lack of heme will result in a lack of negative feedback inhibition on ALA synthase; ramping up the production of ALA.

 

[samson simpson]

See FA P. 354 2011...

It says that in lead poisoning, protoporphyrin accumulates. However, the first step lead poisoning inhibits is ALA dehydratase step. Why wouldn't ALA build up? It seems like with lead poisoning, you can't get beyond that to reach the protoporphyrin.

Related question: What enzyme name will they use on the test for Porphobilinogen ---> Uroporphyrinogen I

I have seen:

Porphobilinogen Deaminase (First Aid default name)
Uroporphyrinogen I synthase
HMB synthase (UWorld)

It would be a lot easier if I only had to remember one name. Anyone know which it is?

 

[gators21]

Bump instead of starting a new thread. It says in FA that aminolevulinic acid accumulates in acute intermittent porphyria and not lead poisoning. Is this true? So if our test only gives us increased aminolevulinic acid is it lead or AIP?

 

[blaqmamba]

http://en.wikipedia.org/wiki/Porphobilinogen_deaminase

"Porphobilinogen deaminase, also known as hydroxymethylbilane synthase or uroporphyrinogen I synthase..."

Lol...two more names to memorize

 

[Anastomoses]

Bump instead of starting a new thread. It says in FA that aminolevulinic acid accumulates in acute intermittent porphyria and not lead poisoning. Is this true? So if our test only gives us increased aminolevulinic acid is it lead or AIP?

In Lead Poisoning both ALA and protoporphyrin accumulate in the urine. In acute intermittent porphyria porphobilinogen and ALA accumulate in the urine.

 

[tiedyeddog]

According to some other sources, ALA does also build up. I'm guessing some ALA builds up because it can't get by the ALA dehydratase step, but the ALA that does get by then builds up behind ferrochelatase and accumulates as protoporphyrin.

This is what I thought, too.