Let's face the naming thing squarely, head on. ADHD and ADD labels provide more confusion than understanding, more complexity than common sense. Why, because they describe symptoms that remain on the surface.
Each one of these 4 neurotransmitters in this list is associated with a link that will take you further down the ADHD neuronal/glial communication path.
If you don't first consider, then measure for specific hormone imbalances you'll remain unconvinced that hormone fluctuations do often create significant ADHD symptoms.