Gee Six Pee Dee Deficiency - Intra/extravascular hemolysis?

[username456789]

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So in RR Path it says G6PD deficiency often leads to intravascular hemolysis, but I'm not sure the "explanation" given was really even relevant.

FA says extravascular, and of course has no explanation, because it's FA.

Anyone have any strong reasoning why it's one vs. the other? In other enzyme deficiencies you usually have deformed cells that get chomped up by splenic macrophages. In G6PD, they eat the Heinz Body but often leave the rest, so you have a Bite Cell. But then what's specifically responsible for the hemolysis? Just the overwhelming oxygen free radicals from whatever precipitates the stress? (i.e. they die before they can even get to the splenic macros to have a bite taken out)

 

[TexasTriathlete]

I say both. You've got the heinz body so the spleen is knocking some of them out, but also there is oxidative damage to the membrane I think that would cause some intravascular hemolysis too.

Both. That's my official answer. Probably wrong, but I can't see how.

 

[DC DOC]

I believe it is both depending on the severity of the damage done to the membrane of the RBC. If the oxidative damage is sufficient to cause a damaging heinz body, it may lyse intravascularly or it may not. If it does lyse then it is intravascular, but if it gets a bite taken out by the RE system then it may revert to a spherocyte or a bite cell, which it then would be eliminated by the spleen after subsequent aging and passing through the spleen, extravascular.

 

[username456789]

Makes sense to me.

Does it often present with spherocytes? I mean it makes sense based on the mechanism (removing some of the membrane), but I'm not sure I've ever come across it in my travels.

 

[PokerDoc]

I think its extravascular bc g6pd deficiency increases the RBC's susceptibility to oxidant stress.. it doesnt do anything more than that..

so no stress = everythings fine

so the hemolysis comes when something outside the cell happens, i.e. all the sudden patient takes a sulfa drug and oxidant radicals screw with the RBCs then the spleen makes a snack out of them. But you need that extrinsic factor or you're not going to get hemolysis all by itself.

 

[turkeyjerky]

Makes sense to me.

Does it often present with spherocytes? I mean it makes sense based on the mechanism (removing some of the membrane), but I'm not sure I've ever come across it in my travels.

nah, it's not the Fc receptor on the macrophage taking out a little piece of membrane--it's a scavenger receptor taking a literal 'bite' out of the cell.

I say it's both intra and extra vascular hemolyis. You'll get a different answer on which one's predominant depending on who you talk to.

 

[donkeyboy]

I think its extravascular bc g6pd deficiency increases the RBC's susceptibility to oxidant stress.. it doesnt do anything more than that..

so no stress = everythings fine

so the hemolysis comes when something outside the cell happens, i.e. all the sudden patient takes a sulfa drug and oxidant radicals screw with the RBCs then the spleen makes a snack out of them. But you need that extrinsic factor or you're not going to get hemolysis all by itself.

i think you mean intravascular hemolysis, a membrane that is more susceptible to oxidant stress as in G6PD def will undergo Intravascular hemolysis not extravascular hemolysis. Though, it's true that splenic macrophages take bites out of the membrane, I don't think the RBCs are actually hemolyzing, they just got bitten, so it's Intravascular hemolysis all the way.

 

[Salpingo]

I believe it is both depending on the severity of the damage done to the membrane of the RBC. If the oxidative damage is sufficient to cause a damaging heinz body, it may lyse intravascularly or it may not. If it does lyse then it is intravascular, but if it gets a bite taken out by the RE system then it may revert to a spherocyte or a bite cell, which it then would be eliminated by the spleen after subsequent aging and passing through the spleen, extravascular.

Yeah, that's pretty much the verbatim explanation given in Robbins.

What I always wondered was why G6PD-deficient people don't have Chronic Granulomatous Disease, or defects in any of the other NADPH-dependent pathways.

 

[C6789]

Yeah, that's pretty much the verbatim explanation given in Robbins.

What I always wondered was why G6PD-deficient people don't have Chronic Granulomatous Disease, or defects in any of the other NADPH-dependent pathways.

Actually, I'm pretty sure they can, depending on the severity of the deficiency. I think I read that in Kaplan biochem.

 

[IMGUSMLEStep1]

Yeah, that's pretty much the verbatim explanation given in Robbins.

What I always wondered was why G6PD-deficient people don't have Chronic Granulomatous Disease, or defects in any of the other NADPH-dependent pathways.

In RBCs, the HMP is the only source of NADPH, therefore when there's no G6PD there is hemolysis.
However, in other cells (that have mitochondria) like WBCs, there are other sources of NADPH (like malic enzyme).

 

[aashkab]

In RBCs, the HMP is the only source of NADPH, therefore when there's no G6PD there is hemolysis.
However, in other cells (that have mitochondria) like WBCs, there are other sources of NADPH (like malic enzyme).

That was money. Are you secretly Dr. Goljan?

 

[Salpingo]

That was money. Are you secretly Dr. Goljan?

Seriously; that was straight up balling.