Understanding ANAs
In order to illustrate this point, I wanted to keep in mind the concerned reader who asked this question in the first place: Amy.
She had mentioned having signs of possible autoimmunity and hypothyroidism, along with lupus.
After updating myself on the latest literature concerning this subject, here is what I found: The best-used autoimmune test, with the most comprehensive data points by far, is known as an anti-nuclear antibody screen (ANA).
In Amy’s exact situation, if we know someone is hypothyroid, we do an ANA test on them and from that ANA test we think they have lupus – that false positive rate is going to be somewhere in the neighborhood of 50 – 100%2.
An Exmaple: Amy
What that means is that if we had 100 people, just like Amy, take this test, and all of them who were hypothyroid had tested positively for lupus – at the very least, half of them do not have lupus. In many cases, none of them would have lupus.