Using PCR analysis a lot recently, so it has been eye opening to understand potential problems with it and also the possibility of false negatives. After listening, you interviewed David Craig about sigA, is there a problem with sigA on a test that uses PCR.? Is DRG accurate? ADAPT student ran one of her daughters who has constant belly complaints. The only thing that showed up of concern was very low sigA 1 to 2.3 and 0.4 sigA. You mentioned that some people or children might have a condition where they could not produce much sigA. Daughter did the BioHealth saliva test 304 that no longer exists at 3 years old. She’s now 6. That showed she had end-range secretory IgA. Does that mean that this is not a concern for her as this is something that could change? How much weight of concern I should put into a low sigA on a PCR test.

Chris Kresser:  Personally, I don’t put a lot of stock into sigA as a marker for determining a specific intervention. I think I said this in the presentations. SigA tends to just be a reflection of other pathologies. I we talked about how Candida and other fungi can reduce sigA level, so it’s very common to see fungal overgrowth markers on stool or organic acids and see low sigA along with that. It’s common to see high sigA in patients with parasites or other gut dysbiosis or issues, which reflects there may be an active gut immune response. There’s not much diagnostic value that sigA adds above and beyond all of those other things apart from telling you that something’s not quite right, and sigA will typically improve as the treatment progresses. It will typically go down if it’s up, or it will come up if it’s low, and there’s not specific actions that you take to lower sigA or increase sigA in most cases unless, as you mentioned, the patient is immunocompromised in some way and just has a decreased ability overall to produce not only IgA but also IgG and IgM maybe IgE. That’s kind of a different concern because you want to look into what conditions can cause that chronic infection or genetic issue that can lead to low immunoglobulin production. Certainly, some more serious issues can lead to that as well. I would be looking, if this were my daughter, I’d be looking at other things like fungal overgrowth, dysbiosis, or SIBO or things that could cause a change in sigA, especially because she has symptoms that reflect that.