That's only valid if the HHV-6 Foundation are referring to the exact lab test you took. If it is a different test or from a different lab, then you cannot necessarily translate titers from one test to another test. I am in the same situation as you, regarding a recent CMV test I did at a London lab. My titers were 206.8 AU/ml, and the lab says < 6.0 AU/mL is negative. So my titers are 206.8 / 6.0 = 34 times higher than the negative value, which seems pretty high, but I cannot be sure that this is considered an active infection. I'd like to use Dr Dantini's rule of thumb, which is that active infection = titers at least 4 times than the average titers for the general population. So I wrote to the lab, asking them for data on average titers for my test, but they did not reply.