During my years as a physician I have had the privilege to work with many families and their autistic children. In my experience, nearly three-quarters of those diagnosed with Autism Spectrum Disorder (ASD) have low thyroid function. With proper treatment, we often see significant gains in speech, language, eye contact, motor function, growth, GI function and socialization. For some children there is a considerable amount of improvement.
Frequently the link between thyroid and autism is tragically overlooked in mainstream medicine. Routine lab tests miss many cases of low thyroid. Lab ranges are inconsistent and constantly changing making it difficult to get a clear diagnosis. Thyroid panels are often inadequate and fail to look at a wide range of diagnostic markers. In other cases, children are on the wrong dose of medication or an incorrect balance of thyroid hormones T3 and T4 due to inaccuracies in the tests used to monitor progress.
Two epidemics on the rise – Two sides of the same coin?
There is a great deal of overlap between symptoms of low thyroid in children and those of ASD such as: speech and developmental delays, cognitive dysfunction, hyperactivity or lethargy, hypotonia/fine motor dysfunction, attention disorders, repetitive motions, social and communication dysfunction, fear, anxiety, depression, GI abnormalities, constipation, feeding and eating problems. For many children diagnosed with ASD, a diagnosis of hypothyroidism is one in the same.
Currently the CDC states that 1 in 68 children in the US has been identified with ASD — a shocking 289.5% increase over the last 12 years. ADHD has increased 33% in the same time frame. One child in six in the US is found to have a developmental disorder including learning disabilities, ADHD, developmental delays and autism.
Likewise, the American Thyroid Association in conjunction with the American Association of Clinical Endocrinologists estimates that 20 million Americans are afflicted with some type of thyroid disease. The vast majority are women with hypothyroidism — 60% of which are currently undiagnosed and untreated. This translates to a lot of moms getting pregnant unaware that they are deficient in thyroid hormones required by a developing baby.
The thyroid gland — a master regulator and catalyst for brain development
The thyroid is a small gland located in the front of the neck producing critical hormones T4 (thyroxine) and T3 (triiodothyronine). These hormones direct the metabolism and energy production of every cell in the body. Having the right amount at the right time is crucial especially for normal brain formation beginning in utero (1).
During the first trimester of pregnancy, the growing fetus is dependent on maternal thyroid hormone for its development. Later, the fetus can produce its own but still relies in part on the mother’s. In both of these phases and continuing after birth, the brain develops under the influence of T3 and T4 regulating the proliferation, migration and differentiation of neurons in specific brain regions at specific times. Deficiencies in either the mother’s supply or the baby’s can have grave consequences leading to behavioral, developmental and cognitive issues for the child.
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A recent study published in the Journal of Physiology and Pharmacology made some incredible advances in our understanding of the autistic brain and how it relates to thyroid (2). Postmortem brains of children age 4-16 were studied against age-matched controls. It was found that levels of T3 were low in localized critical regions of the brain in the ASD children. This deficiency may not occur in the rest of the body. Further, the expression of several thyroid hormone dependent genes was altered in ASD and oxidative stress was increased.
Similarly, there have been other studies looking at other conditions like Alzheimer’s and reflux finding thyroid hormone levels to be normal when tested in blood yet low in affected tissues— in these cases, the brain and the esophagus. Routine tests will be useless in these cases since blood levels will appear normal.
More links between the brain, ASD and low thyroid
The brain and thyroid tissue are both very susceptible to damage from the same sources.
Toxicity – Endocrine disrupting chemicals (EDCS) are substances that interfere with production and function of endocrine hormones such as thyroid hormone. Lead, mercury, cadmium, perchlorate, phthalates, PCB’s, pesticides, bisphenol-A and dioxin can disrupt things by blocking or mimicking hormone signals, scrambling the messages sent to cells and also by tricking the endocrine system to accept new wrong instructions. This is especially problematic when considering the delicate timing of hormone-controlled brain development in the fetus (1). Studies have linked many of these same chemicals to autism pathology.
Gluten – At the present time the autism community is well versed in the connection between gluten intake and the severity of symptoms. A gluten-free diet is considered a front line defense and often one of the most effective treatments for children with autism. Gluten has also been linked to thyroid disease especially an autoimmune condition called Hashimoto’s Thyroiditis which is the primary cause of hypothyroidism. Gluten-free diets have been shown to heal this attack on the thyroid often resolving the issue for many (3).
Putting it all together — the proper and accurate thyroid evaluation
Currently doctors rely on a single test to measure the level of TSH in blood. A high level is diagnostic for low thyroid function. As described earlier, there are problems with lab ranges and tests miss a large percentage of cases. I use a much more accurate test called the TRH challenge. In cases of low thyroid, even if TSH levels are normal in the blood, it will unequivocally be high in an area of the brain called the pituitary gland (4). TRH prompts the release of stored TSH into the blood where it can be easily detected and measured. By asking the pituitary to “show it’s cards” so to speak, we get a clear understanding of how thyroid hormone is actually functioning in the body and in the tissues that need it. It is also a far more precise way to evaluate the accuracy of thyroid medication dosing.
In my findings, approximately 75% of low thyroid function is missed in children with autism and other developmental disorders using routine testing alone. A comprehensive evaluation of the thyroid is essential to proper care. A full thyroid panel should include levels of TSH as produced through the TRH challenge, free T3 and T4, total T3 and T4, Reverse T3, and very importantly levels of thyroid antibodies TgAb and TPOAb.
If you suspect your child has ASD or is showing signs of possibly being on the road — don’t wait. Find a doctor who fully understands the connection between thyroid and the brain and get properly tested. It’s never too early to begin treatment and fuel the brain with needed thyroid hormone.
I also urge any woman thinking of getting pregnant to have a thorough and comprehensive thyroid evaluation. If you experience any of the classic symptoms of low thyroid like unexplained weight gain, depression, anxiety, hair loss, fertility issues, dry skin, constipation but the routine tests show nothing is wrong, seek out a doctor who can help you get properly diagnosed.
Porterfield SP. Vulnerability of developing brain to thyroid abnormalities: environmental insults to the thyroid systems. Environ Health Perspect, 1994 Jun; 102 (Suppl2):125-30
- KHAN et al, Disrupted Brain Thyroid Hormone Homeostasis And Thyroid Hormone-Dependent brain Gene Expression in Autism Spectrum Disorders, Journal of Physiology and Pharmacology 2014, 65,2. 257-272
- Mainardi E, Montaneli A, Dotti M, Nano R, Moscato G. Thyroid-related autoantibodies and celia disease: a role for a gluten-free diet? J Cin Gastroenterol. 2002 Sep, 35(3)
- Suhail A.R. Doi, et al, TRH Stimulation When Basal TSH is Within the Normal Range: Is There “Sub-Biochemical” Hypothyroidism? Clin Med Res. 2007 Oct; 5(3): 145–148.
This article was featured in Issue 38 – Keeping ASD Kids Healthy