What tests might my child's pediatrician request?

The tests your child's doctor asks for will depend on your child's situation. Often, children with ASD have vision, hearing, and blood tests including genetic testing. If your child has seizures, your child's doctor may ask for neurological tests, which are tests of the brain and nervous system. Your child's pediatrician may send your child to a specialist for tests for gastrointestinal or sleep symptoms.

How will my child's pediatrician decide which tests are needed?

Your child's pediatrician will look at how your child is developing and acting now and in the past. Also, she will look at whether your child's body or growth shows any differences. This will help her decide which tests to ask for. Only tests that provide useful information should be requested. For some children, very few tests will be needed. Some of the tests that may be asked for are discussed later on.

Why are hearing tests needed?

All children with ASD should have a hearing test to rule out hearing loss that could explain speech delays. Most infants have a hearing test near the time of birth, but another test is needed for any child with speech delays, even if the one at birth didn't show any hearing loss. The doctor should ask for a hearing test for any child with language delays or possible ASD.

There are many reasons why a child can lose some hearing during the first few years after birth. While hearing loss does not cause ASD, it affects how your child communicates. Rarely, children with severe hearing loss show behaviors like those of children with ASD.

Why are blood tests needed?

Your child's pediatrician may ask for blood tests to help understand the cause of your child's ASD, especially if your child has delays in many areas. Sometimes it is hard to tell whether children with ASD have some kinds of delays because they often have a hard time cooperating with testing. Blood tests are usually requested to look for a difference in your child's DNA that might cause ASD. As of now, DNA changes can be found in up to 10% to 20% of children with ASD. Tests could include a chromosomal microarray analysis to find small areas with extra or missing pieces of DNA and testing for fragile X syndrome.

Fragile X syndrome is found in about 1 out of 100 children with ASD.

Some children with ASD, mainly those with many delays, may have differences in the development of their facial features, hands, feet, and skin. If your child's pediatrician notices any of these things, more blood tests may be requested. This is to see if these findings are really clues for rare genetic syndromes associated with ASD. A syndrome is when a group of physical differences occur together.

Your child's doctor may also look at your child's birth records to make sure all the newborn screening test results were normal. If these cannot be found, new tests may be requested.

Why are neurological tests needed?

Some children with ASD may have seizures. Others may have movements of their face, hands, or arms that they cannot control that are not seizures. If your child's pediatrician thinks your child has seizures, he will likely refer your child to a neurologist—a specialist of medical problems that affect the brain. The neurologist may request electroencephalography (EEG) to study how your child's brain works.

Your child's head may be larger or smaller than average. Young children with ASD tend to have a larger than average sized head.

Your child's doctor or the specialist will decide whether a special radiology test called magnetic resonance imaging (MRI) should be done to look for any differences in the way your child's brain formed. This is more likely to be done if your child has a very small head or a difference found during examination.

The tests MRI and EEG may not be useful for every child with ASD.

Neurological tests may also be done to find the cause of loss or slowing of developmental milestones. About 1 in 4 children who has ASD appears to develop normally and then lose skills or stop developing new skills for a while. This is called regression. Autism regression often happens between 15 months of age and 24 months of age, and researchers do not know why. If your child is tested during one of these periods, your child's doctor may request EEG or MRI. If your child has stopped regressing and is now making progress in development, these tests may not be requested.

What other tests might my child need?

If your child is often sick with vomiting and unusual weakness during flulike illnesses, your child's pediatrician may suspect a biochemical disturbance and refer your child to a metabolic specialist or clinical geneticist for more testing.

Many children with ASD tend to put things other than food into their mouths even when they are older. If your child does this, your child's doctor may request a lead level test, especially if your family lives in a high-risk area. Lead does not cause ASD, but toxic levels can both harm learning and make ASD symptoms worse. Iron deficiency may also make children put things other than food into their mouths. Your child's doctor might look for iron deficiency with laboratory tests. Low iron levels might be related to poor sleep.