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Old 06-19-2012
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Default why c4 levels are normal in PSGN ?

serum C3 and CH50 levels are low , while the C4 level is normal (this indicates the activation of the alternate
complement pathw ay)
this is excerpt from a book in context of PSGN. i cud not get it. so can any1 please please explain why C4 is normal in PSGN !! thanks.
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Old 06-19-2012
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Hi i also dont understand and dont agree with the statement.

Hi generally speaking you have 3 pathways to activate complement system.
Lest focus only on the classic and alternative.

It's true that alternative has nothing to do with C4, the C3 convertase is actually made from C3 and B factor.
But in PSGN (you mean post streptococcal right?) anyway here it's mediated by antigen-antibody immune complex so it activates the classic pathway.
Because of that C3 and C4 will be decreased as the C3 convertase is made from C4b and C2b.
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