Yes, it can be confusing, and most doctors can't tell either.

Too little B6 leads to neuropathies. Then there is the very high doses which over time, can also cause nerve damage...which I believe is a bit different in presentation. A very fine difference.
B6 has this paradoxical problem which makes it very difficult to
diagnose, using symptoms.

If you are not converting pyridoxine to pyridoxal in the body then pyridoxine would build up, not be working biologically for you and show up in serum tests. If you stop the Bcomplex 100mg, and just take the P5P for a while--- most P5P's are not that high dose, you can see if you feel better. A multivit for the rest of the B's, could suffice. NOW brand is enteric coated and not expensive. Available on iherb.com
You'll want enteric coated because P5P is sensitive to stomach acid. Stay below 100mg a day, and you should be okay.
B6 pyridoxine requires B2 riboflavin to convert to active pyridoxal (using the enzyme pyridoxal kinase).
http://www.iherb.com/Now-Foods-P-5-P...blets/740?at=0
(this is an example).'

The hint here is that a study was done on autistic children, who were NOT taking any supplements. And they scored high in serum B6. That suggests something is "wrong", but the answer has not been confirmed as yet. So testing B6 is not like testing Digoxin or phenytoin, or lithium levels. With drugs, there are clear cut protocols that have been put in place before they were put on the market.

There might be an answer in some obscure text somewhere, but I haven't found it yet regarding the B6 lab ranges.
And the bottom line is that there have been very few, rare cases of toxicity documented at all.