SCA causes decreased Haptoglobin????

[NoWayOut]

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OK.. so I get this q on UW about SCA and one of the choices were "decreased haptoglobin".. I didn't chose that because according to Goljan, haptoglobin is decreased when you have Intravascular hemolysis and SCA is an extravascular hemolysis. I get the question wrong anyway..and in the explanation it says that SCA causes reduced haptoglobin. I am thinking ..well why? The hemolysis occurs in the spleen most commonly, not inside the blood vessels. The only reason haptoglobin is released from the liver is to bind free Hb floating in the Blood. But that is not the case in SCA, right? The spleen takes care of the Hb there breaking it down into Iron and protopophyrin, and globin chains.
Unless SCA is causing some crazy vaso-occlusiveness to the liver, leading to damage that I don't know of and decreasing the production of haptoglobin, then I don't know why it would decrease haptoglobin 😕
Any idea folks??????

 

[MoscowAbe]

The same reason why SCA can cause vasoocclusion in the peripheral arteries, so obviously those damaged RBC's can be found in the peripheral blood circulation as well where they lyse resulting in free Hb to be taken up by haptoglobin.

 

[IMGUSMLEStep1]

RR Path says that in SCA, hemolysis is predominantly extravascular. However, that doesn't mean it is only extravascular. Some intravascular hemolysis also occurs.

 

[NoWayOut]

RR Path says that in SCA, hemolysis is predominantly extravascular. However, that doesn't mean it is only extravascular. Some intravascular hemolysis also occurs.

Yes I suppose you are right. I will need to keep this in mind because I tend to go with what's common.
Thanks.
BTW..when is your exam ?

 

[turkeyjerky]

haptoglobin is typically reduced in extravascular hemolysis too. goljan is wrong on this one (one of the few areas of heme where he's not money). whenever the macrophages in the spleen start chewing up those rbc's, a little bit o' heme leaks out and causes a reduced haptoglobin.