How often do you rely on using the C1 inhibitor functional assay versus the quantitative level alone to diagnose HAE?

We have seen a significant increase in lab costs billed to well-insured patients for some of the more "esoteric", detailed testing associated with immune/inflammatory disorders such as HAE. The cheapest screen is a C4 level, which, if normal during an active angioedema episode, makes C1 inhibitor de...

Should always use both since the functional assay distinguishes between Type 1 and Type 2 HAE.

An interesting question. I have only ever ordered both C1 Inh level and function, along with C4, and not just the level. The majority of HAE patients will have type I HAE, with low quantitative levels, while a minority (about 15%) will have normal levels but dysfunctional protein, or type II. Thus, ...