Depending on what version of excel you're running, there's a =GetPivotData()
function.
But when I do this, I'll either convert the pivottable to values (or a copy of
the pivottable). Then I'll fill those empty cells to the left and use that for
my lookup table.
If that sounds reasonable, take a look at Debra Dalgleish's site for some tips
on how to fill those empty cells: