In my opinion, it should never be done. ADHD is simply a subjective psychiatric label. There is no objective test for it. The teachers and parents fill out a checklist of symptoms. No lab is drawn, no physical exam is usually performed. Most doctors just look at the checklist and give the diagnosis and a prescription for a drug. Nowhere else in medicine does this occur. To diagnose someone with hypertension, the doctor takes the blood pressure. It is an objective test. To diagnose someone with diabetes, the doctor draws blood. It is an objective test. Only psychiatric diagnoses lack objectivity.