It certainly is discouraging if ANA is negative assuming the GP's office was right. The RF is neither here nor there, except it suggests that RA is not the problem.
I think your chronic urticaria and this swelling of the mouth tissues could be very significant. The swelling could be a form of angioedema. You might want to think if the mouth swelling is ever associated with tummy pains ore even genital discomfort. I have heard of cases when chronic urticaria has preceded a lupus diagnosis for years.
The relevant tests are for a protein called complement.
Complement testing is a common feature of the more specialist tests for autoimmune disease or immune disorders. Complement plays an essential role in the immune system activity. Low complement in SLE can indicate active disease or a flare.
Then there are inherited or acquired complement deficiency states which might be associated with lupus or lupus like symptoms. Mind, they are rare but all the same, on the leave no stone unturned principle, it's a line worth pursuing.
You could always casually throw out the words ' I was wondering about complement deficiency ' to the doctor ! :lol: He might be rather surprised but good doctors don't mind informed patients and it is a perfectly reasonable question. You could always say, quite truthfully, that a friend mentioned it as a possibility.
The relevant tests are C3 and C4, and a C50 or C100 is usually done, I believe. A particular deficiency is of C1 esterhase inhibitor.
I happen to know about this because one day my daughter's lips started swelling. She had gone upstairs to get ready for a night out looking perfectly normal. After about 15 minutes, she came down rather distressed with her mouth already looking like a really bad collagen injection. As we spoke, her lips visibly continued to swell so we rushed her to A&E. They kept her in overnight with a drip feed thing in her hand incase they needed to IV antihistamine but she was OK.
We never found out what caused it but the strongly suspected culprit was an aspirin she'd taken at a friend's house. We have never used aspirin in our house and indeed rarely needed that sort of thing.
Aspirin is a common trigger for this sort of reaction. It could be useful to keep a food diary to see if the swelling has any connection with food. 'Aspirin' occurs naturally in quite a few foodstuffs !
I mentioned this to my then rheumatologist who was very interested indeed. He asked if she had any lupus like symptoms and had ever had this before.
Then there's something called hypocomplementic urticarial vasculitis, HUV. We have threads about it on Related Conditions section.
Biopsies show up certain sorts of cell deposits in the skin that can help distinguish what's causing a particular sort of problem. Sometimes there might not be any particular indication in blood work, other times the biopsy would be confirmation of what's already suspected from symptoms and blood work, so the right treatment can be given
All the best