why is c3 normal in hereditary angioedema

[IM/EM/CCM]

Since C3 is the common for all pathways, why is it normal in C1 INH esterase deficiency (aka Hereditary angioedema)?
If C3 is consumed, shouldn't it be decreased?

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[cellsaver]

Since C3 is the common for all pathways, why is it normal in C1 INH esterase deficiency (aka Hereditary angioedema)?
If C3 is consumed, shouldn't it be decreased?

You are misunderstanding the role of C3.

There are 3 complement pathways: Lectin, Classical and Alternative. C3 is the focal point of the 3 pathways. All 3 pathways generate the enzyme C3 convertase which cleaves C3. The cleaved C3 releases C3a while C3b remains attached to the microbial surface. C1 is not involved in the Alternative Pathway nor the Lectin Pathway. The following figure should help.

See Janeway's Immunobiology website, Chapter 2, for free powerpoint slides of the classic textbook, videos and flashcards.

Janeway's is one of the more popular immunology textbooks in many medical schools. Consult your school's immunology textbook