CH50 test?

[ZIZOCOOL]

So I was reviewing the complement pathway and saw the CH50 test.

A quick google search says "One CH50 unit is defined as the volume or dilution of serum that lyses 50% of erythrocytes in the reaction mixture." and "Low levels of CH50 or AH50 warrant further evaluation."

Now, why does low levels warrant further tests? If lower volume of serum is required to lyse 50% of erythrocytes doesn't that mean that complement is more concentrated (no defeciency)?

Thanks

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[Pepe18]

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[ZIZOCOOL]

I remember having trouble with this test because everything about it is written so vaguely.

I think they are talking about dilution in terms of the rbcs. So a low dilution is a lot of pt serum:rbc. Like 10ml of pt serum needed to hemolyze 50% of 1mL of rbcs represents lower complement activity than 1ml of pt serum serum for hemolyze 50% of 1mL rbc

The most important thing is all complement proteins 1-9 need to be present for it to work and low means autoimmunes diseases what have immune complexes, etc.

Thanks a lot