I don't know the answer but I do know that's one reason to do bloods on a regular basis. Unfortunately practices like this tend to stress the bodies limits but so long as we are aware of where we stand and have the knowledge on how to remedy things then that's the best we can hope for. If we want to continue doing what we do that is.
On a similar thought, I'd venture to say that we are probably more in tuned with our bodies than the average person walking the streets. We take the time to read and learn and test and ask etc. Most people don't know what's going on in their own bodies and that's a shame. If they're lucky they go to a MD once a year to get a physical and if they;re told all is ok, then they're good. Personally I've always wanted to know more of the why and how.