The fact that the child exhibits ADHD-like behaviors does not prove that they are suffering from this disorder. It is quite possible that some other problem is causing these symptoms. In order to correctly diagnose ADHD, the doctor must first rule out these "look-alike" factors by conducting a thorough physical examination and administering laboratory and other diagnostic tests:

Medical conditions.

Allergy and effects of allergy medication, hearing loss, thyroid disorders, visual disturbances, genetic disorders (such as Fragile X syndrome), seizure disorders and chronic medical conditions.

Mental disorders.

Anxiety disorders, conduct disorder, depressive disorders, oppositional defiant disorder, pervasive dvelopment disorder or Tourette's syndrome.

Behavioral and neurologic conditions.

Articulation problems, coordination problems, encopresis (a type of soiling problem whereby children defecate in inappropriate places), enuresis (bed-wetting), night terrors and sleep difficulties.

Learning and language disabilities.

 Difficulties with listening, speaking, thinking, reading, writing, reasoning and performing mathematical calculations.

Additionally, the doctor will take a thorough medical history and consult rating scales to confirm ADHD. The history should include a family, birth and general medical history gathered from family as well as school and day-care (if applicable) workers.