The FAA recommends that potential pilots do a urine analysis to show they don’t have any substances/enhancers in their system when they take the ADHD test. They also recommend that the pilot give their complete medical records to the psychologist. I have probably done 15 or so of these and haven’t run into any problems. See the below link
Here is a PIlot statement for the website: Pre-psychological screening for pilots is a precautionary standard of the Federal Aviation Administration (FAA) when the candidate has a history of psychological concerns/disorders, or Attention-Deficit Hyperactivity Disorder. Your assessing medical physician will work with us, and it is understood that our final evaluation will be released to this physician. There are times when a medical background and/or urinalysis may be required. Selected tests and procedures are determined by the needs and background history of the aviator.