There is no lab test or X-ray that can confirm the diagnosis of autism. The diagnosis of autism is based on clinical judgment regarding observations of the individual's behavior. Information from family members and other observers is of primary importance in making the diagnosis; however, the pediatrician may order tests to rule out other conditions that might be confused with autism, such as mental retardation, metabolic or genetic diseases, or deafness.
A single visit with the pediatrician is not enough to establish the diagnosis of autism.
How to Diagnose?
The pediatrician observes the child and may do a simple screening test to see if a developmental problem may be present. Screening tests do not diagnose autism. Done in the office, they are simple tests that indicate a problem may exist. They usually involve simply observing specific behaviors (for very young children) or how a child responds to simple commands or questions (for older children). Some widely used screening tests include the Checklist for Autism in Toddlers (CHAT) for children aged 18 months to 4 years of age and the Autism Screening Questionnaire for children aged 4 years and older.
Other conditions must be ruled out, and the diagnosis of autism must be established with certainty before treatment begins.
If the pediatrician believes that further evaluation is necessary, he or she will refer the child to a professional who specializes in developmental disorders. This specialist may be a developmental pediatrician, a child psychiatrist, a pediatric neurologist, or a child psychologist.
Other professionals, such as speech and language pathologists, audiologists (specialists in testing hearing), occupational therapists, physical therapists, and social workers, may be involved in the evaluation process.
The comprehensive evaluation of a child with autism might include:
obtaining complete medical and family history;
formal audiology evaluation;
selected medical/lab tests on an individual basis (for example, lead levels, genetic tests, metabolic tests, brain MRI, electroencephalogram [EEG]);
speech, language, and communication assessment;
cognitive and behavioral assessments (focus on social skills and relationships, problem behaviors, motivation and reinforcement, sensory functioning, and self-regulation); and
academic assessment (educational functioning, learning style).