The full blood work up to look at the immune system involves about 12 vials of blood! If she wanted to look at this, she'd need to see a proper immunologist (and preferably one who takes an interest in allergy as well) as it's much more complicated and subtle that just looking at her white blood cell count.
Has she had her biopsy results back? If there are MAST cells present in the sample, that could indicate an immune system response problem. These problems are usually multi-factorial. MAST cells in the biopsy could indicate a problem with her response to histamine - either her body is producing too much of it, or that she is responding too much to histamine (I forget which - it really is very complicated!).
If she wants to start eliminating foods, looking at this might be useful:
www.allergyuk.org/common-food-intolerances/histamine-intolerance
I did an exclusion diet for IBS a number of years ago. It was hard and annoying to do, but it was quite interesting and I found out some things that would not have struck me as affecting me - e.g.potatoes were disastrous, but sweet potatoes were fine; lettuce was a no-no, rocket was good.
Has she has skin-prick or blood tests for allergy?
Sorry - am reading your posts out of order and consequently things are occurring to me randomly. You said that no bacteria are present (I presume in her urine). Testing is done to detect bacteria at a certain level and my uro-gynae explained that the bar for most testing is set too low (I cannot remember what the numbers are) and that when you test 'negative' urine to detect bacteria at a lower level, you get a positive result. Even then, a negative result might not mean that no bacteria are present in the sample. He also said that with infections that involve inflammation of the bladder wall, the bacteria can happily reside there even though there may be no bacteria showing up in the urine. So, again, a negative urine sample doesn't necessarily mean no infection.
In my case, abx keep the bacteria at bay. The keep the levels low enough that my symptoms improve and I pretty much feel normal. If I come off them, within a month, the levels have risen and are high enough for my symptoms to return. This could be what is happening with your DD. Which antibiotics has she been on? How long for? Has she been on different ones in rotation, or just the same one?
It's horrible.
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