C1q autoimmune blood test

[Tulipano]

On my last two blood test I had a positive c1q autoimmune. Do you know what that means and in what other disease apart from lupus can be positive? Thanks

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rarediseases.info.nih.gov/d...

I just googled and found this.

[Melba1]

Hello, I hope this makes sense - I’ve spent the last few months researching it as I had similar and my GP and neurologists admitted they didn’t really understand...

So C1q is part of the complement system which is the part of the immune system you were born with. It is made up of little proteins going from C1q, C1r/s, C2 etc up to C9 that work in a sort of chain when your body responds to any germs.

There are two things that often effect those of us with lupus:

1. Some of us are born with very low/ no levels of one part of complement (usually C1,C2 or C4) which makes us more likely to get lupus and our levels of that one will always be low.

2. Lots of us will get lower levels of these early parts of complements in a lupus flare but in this case they will return to normal when the flare is under control.

If your C1q is called anti C1q on your results this is an antibody against the C1q protein which means it’s attacking it so will probably be making the levels low. Lots of people with lupus have this.

I have my total complement levels (called CH100 or CH50) tested and they are always very low so just being tested now to see which one of the ‘Cs’ is low/ missing for me or whether it’s just because I’m in a flare.

It’s worth asking to get this CH100 and a test called a functional test of all the parts of your complement system.

I think if you just have a problem with C1q it might be that you were born with that and most people (over 90%) with that will get lupus. If all of them are low at the moment it is more likely to be a sign of a flare.

I’m not sure of other diseases associated with it but think those of us born with low/ no levels of one complement will usually have had more infections as a child and be more likely to get lupus.

Most hospitals only routinely check C3 and C4 levels but for those of us with C1 or C2 problems it’s worth getting the whole system checked.

Hope that’s helped - sorry if it’s not very clear. I don’t think it’s a very understood area of medicine!!

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