If you do not stop vitamins for about a week, they will register in tests as a false high.

B6 is stored for a short time in muscles, as pyridoxal and this may be a source for serum elevations. However there is a study on PubMed done with autistic children, who tested high in B6 when there were no vitamins being taken. This could be a feature of a metabolic error in that population we don't understand yet, or it could be from fortified foods. Many foods have B vitamins added.

Doctors do not understand lab ranges of nutrients at all. I wouldn't expect much useful advice from them on this subject.
The ranges were made from statistics gathered from people at random who were NOT taking vitamins. One would expect higher results when supplements are being used.

Intracellular testing labs measure what is inside cells, and not just the serum, like the common tests use. This is thought to be more accurate.
This lab does more accurate testing:
http://www.spectracell.com/