Special Needs


Laboratory Tests—Autism Toolkit

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Why would my child need laboratory tests?

All children have some laboratory tests at birth and as part of regular checkups. Children with autism spectrum disorder (ASD) often need more tests. These tests can help find the cause of the condition or problems related to it that may not be obvious. This helps guide your child's doctor in treating your child best.

New genetic tests now make it possible to find a cause for ASD in many more children than before. Genetic testing can also give information about the chance of ASD in future children or for children of other family members.

What tests might my childís pediatrician request?

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

How will my childís pediatrician decide which tests are needed?

Your childís pediatrician will look at how your child is developing and acting now and in the past. Also, she will look at whether your childís 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 didnít 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 childís pediatrician may ask for blood tests to help understand the cause of your childís 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 childís 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 childís 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 childís doctor may also look at your childís 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 childís pediatrician thinks your child has seizures, he will likely refer your child to a neurologistóa specialist of medical problems that affect the brain. The neurologist may request electroencephalography (EEG) to study how your childís brain works.

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

Your childís 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 childís 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 childís 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 childís 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 childís 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 childís doctor might look for iron deficiency with laboratory tests. Low iron levels might be related to poor sleep.

The information contained in this resource should not be used as a substitute for the medical care and advice of your pediatrician. There may be variations in treatment that your pediatrician may recommend based on individual facts and circumstances. Original resource included as part of Caring for Children With Autism Spectrum Disorder: A Practical Resource Toolkit for Clinicians, 3rd Edition.

Inclusion in this resource does not imply an endorsement by the American Academy of Pediatrics (AAP). The AAP is not responsible for the content of the resources mentioned in this resource. Website addresses are as current as possible but may change at any time.

The American Academy of Pediatrics (AAP) does not review or endorse any modifications made to this resource and in no event shall the AAP be liable for any such changes.