The Thyroid-Autism Connection

The center for Disease Control and Prevention (CDC) has found that 1 in 100 children in the US have been diagnosed with Autism Spectrum Disorder or ASD, up from 1 in 150 in 2007. A study in the Journal of Pediatrics in October 2009 revealed similar numbers. Parents of 1 in 90 children reported that their child has ASD is now 1 in 58. Autism is the fastest growing developmental disability affecting more children than cancer, diabetes, and AIDs combined.

Another disease reaching epidemic proportions is thyroid disease. According to a study published in the Journal, “Cancer” July 13, 2009, thyroid cancer doubled in the last 10 years. Some researchers feel that the significant increase in thyroid cancer is related to the significant increase in auto immune thyroid disease that goes untreated. Subclinical hypothyroidism associated with an elevated TSH can stimulate the thyroid gland, leading to the increased risk of cancer. Additionally, according to researchers, if the upper portion of the normal range of TSH (the routine thyroid blood test) was lowered to 3 as The American Association of Clinical Endocrinologist (AACE) recommends, approximately 20% of the population would be hypothyroid.

One doesn’t have to look very deeply to appreciate that these two disorders are interconnected. Firstly, both are associated with the increasing burden of environmental toxicity. Both the brain and the thyroid are very susceptible to toxins. Additionally, neurotoxins such as PCBs and Dioxin, likely to be associated with neurological disorders such as autism, exert some of their effects on the brain through their effects on the thyroid. Hypothyroidism can have a profoundly deleterious effect on the developing brain, thus significantly contributing to the web of causes of autism. Other toxins which can contribute to both autism and hypothyroidism include lead and mercury.

According to a study published in the Archives of Internal Medicine, 1983, 143 (2) 220- 224 lead, a heavy metal commonly found in children with autism and ASD can also cause hypothyroidism. Mercury, another metal associated with autism and ASD, can also cause hypothyroidism, and researchers address the possibility that high exposure to mercury may perturb neurodevelopment processes by selectively affecting thyroid hormone function. Thus, many of the neurotoxic effects of mercury may be mediated through the thyroid as well. Hypothyroidism can also lead to impaired detoxification, leading to secondary buildup of lead and mercury.

There are yet other reasons to believe that there is a thyroid-autism connection. Celiac disease and gluten sensitivity, known to be a factor contributing to autism, is also associated with other autoimmune disorders such as autoimmune thyroiditis, a cause of hypothyroidism. One of the most effective therapies for autism, ASD, and PDD is a gluten free diet. Studies show removing gluten can also heal secondary autoimmune disorders such as hypothyroidism. Perhaps one of the reasons why the gluten free diet is so effective in children with autism is that it can help heal the underlying thyroid disorder.

Thyroid hormone is essential for normal brain development during a critical period beginning in utero and extending through the first 2 years post partum. It regulates neuronal proliferation, migration, and differentiation in discrete regions of the brain during definitive time periods. Thyroid hormone also regulates development of cholinergic and dopaminergic neurons in the brain. Deficiencies in thyroid hormone during this critical time can have significant behavioral and cognitive effects.

Thyroid disease in children and autism therefore have many overlapping signs and symptoms. These include but not limited to:

  • Feeding problems
  • Prolonged jaundice
  • Poor muscle tone
  • Gastrointestinal abnormalities
  • Constipation
  • Sleep disturbances
  • Developmental delays
  • Trouble holding up head
  • Protrusion of belly
  • Hyperactivity
  • Lethargy
  • Lack of play and interaction with others
  • Dry skin
  • Poor Hair Growth/Bald spots
  • Pale complexion
  • Frequent infections
  • Cold intolerance
  • Cold extremities
  • Weight gain
  • Difficulty gaining weight
  • Allergies
  • Bed wetting
  • Poor bone development
  • Fear
  • Anxiety
  • Depression
  • Decreased ability to concentrate
  • Speech delay
  • Fading of the personality’s color and vivacity
  • Progressive loss of interest and initiative
  • Slowing of mental processes

Other researchers are beginning to appreciate the thyroid- autism connection as well. A study done in the Royal Berkshire Hospital showed that out of 62 autistic children, 45 were found to be hypothyroid. In a study published in the Journal of Child Psychology and Psychiatry 5 children with autism were evaluated. Three were shown to have hypothyroidism and two had mothers who had probably been hypothyroid in pregnancy. The researchers concluded that “thyroid hormone deficiency in early development might cause nervous system damage such that autistic symptoms are likely to ensue”.

If thyroid disease is a major contributor to the web of causes of autism, why is it not widely known? The answer is that the routine thyroid blood tests frequently fail to detect the problem. The routine thyroid blood tests TSH, T4, and T3 are notoriously unreliable. Even the American Association of Clinical Endocrinologists (AACE) have realized that the TSH reference range (the most relied upon thyroid test) has been too wide and has missed detecting low thyroid in a large percentage of patients. What experts have come to realize was that the upper TSH normal range has included people who actually have mild thyroid disease and their higher TSH levels skewed the curve. This understanding led to the recommendation in Jan. 2003 by the AACE that doctors consider treatment for patients who test outside the boundaries of a narrower margin based on a target TSH level of .3 to 3.0. The American Association for Clinical Chemistry, or AACC, feels that the upper limit of the TSH range should be reduced to 2.5. Yet most doctors are unaware of these new guidelines.

Even the new range of .4 to 2.5 for TSH is very narrow and it is likely that even this could miss a large percentage of patients. We know that TSH tests on any given patient can vary on any given day. Additionally many patients with TSH in one range of .4 to 2.5 have symptoms of low thyroid. This has led many doctors to abandon the routine test altogether and instead many use body temperature to diagnose hypothyroidism. This is called the Broda Barnes method. Unfortunately, it also misses the mark for many patients especially children with low thyroid, have a normal body temperature. To make matters even more complicated many people who clearly have hypothyroidism based on the fact that they have many of the classic symptoms, have TSH values between 1 and 2.5.

There is another more sensitive thyroid test called the TRH stimulation test which in the past was the standard thyroid test. This test uses a hormone called TRH which stimulates the pituitary gland. The pituitary makes a hormone called TSH which stimulates the thyroid to produce thyroid hormone. If the thyroid is low one would expect that the pituitary would be producing a lot of TSH which would be reflected in the blood as high TSH. However, frequently, due to various mechanisms, even if one has hypothyroidism the TSH does not go up in the blood, rendering the routine thyroid blood test inadequate in a significant percentage of patients. However, even if the blood levels of TSH can be normal in hypothyroidism, unequivocally the TSH will be high in the pituitary gland itself. Upon stimulation with TRH the TSH would be released on the spot, rising to high levels, allowing us to make the diagnosis. This avoids the pitfalls of measuring routine blood levels that can be misleading and inaccurate.

I have used the TRH test in over 15,000 patients with symptoms of hypothyroidism and have diagnosed hypothyroidism in a large percentage.

With treatment they saw significant improvement. Without this test the diagnosis would have been missed. Additionally, based on the TRH stimulation test in hundreds of children with autism, ASD, PDD, and other developmental disorders I have found that 75% have hypothyroidism that was missed by the routine test. With treatment using thyroid hormone the children experienced significant improvement in focus, speech, eye contact, interaction with others, attention, cognition, and mood. In fact there is no other treatment for autism that is as effective as thyroid hormone. Yet, unfortunately, most doctors, even Defeat Autism Now! doctors are missing the critical diagnosis of hypothyroidism in children suffering from autism, ASD and PDD and other unexplained problems because they are relying on the routine thyroid blood test.  Many doctors are even still using the old reference range for TSH of 0.4 – 5.  If one misses this diagnosis of hypothyroidism in these children, then one of the most significant factors in the etiology of their disorder will be left untreated and the brain will not be able to develop normally.

In a study published in Gynecological Endocrinology titled “Subclinical Hypothyroidism in Infertile Women, the Importance of Continuous Monitoring and the Role of the Thyrotropin Releasing Hormone Stimulation (TRH) Test,” Israeli researchers proved that women who have fertility issues who have normal TSH need the TRH stimulation test. They came to this conclusion based on the fact that a significant percentage of women with infertility had a normal TSH and an abnormal TRH stimulation test. The researchers recommend performing TRH stimulation testing in women suffering from ovulation disorders and infertility that have normal based TSH levels.

According to a study published in Clinical Medicine and Research in 2007 titled “TRH Stimulation when Basal TSH is within the Normal Range; Is there “Sub-Biochemical Hypothyroidism?” researchers concluded “we document that an exaggerated TRH response indeed occurs in many patients with a normal biochemistry… Even though the TRH test is seldom used in clinical practice at present, a larger prospective study is in order. Until then, physicians may once again need access to TRH for diagnostic use.”

John was diagnosed with ASD at the age of 3, fortunately he benefited from this frontier findings and research. He exhibited delayed speech, poor eye contact, poor cognition and hyperactivity, and he showed less interest in play than his peers. He had low muscle tone from birth. He also had chronic constipation and bloating. The TRH test I performed showed unequivocal hypothyroidism. I started him on thyroid hormone, compounded T4 and T3. Within only a few days, his hyperactivity diminished significantly. Within a few months his language and cognition increased, as well as his general interest in things. His occupational therapist observed a few months later that he never saw such a significant change in any child suffering from autism.

Kevin is a 7 year old boy who was diagnosed with autism at age 3. He did biomedical treatments and only saw mild results. When I saw him I did the TRH test and discovered his thyroid was low. I started him on a compounded thyroid hormone. Within a few months Kevin’s life began to improve dramatically. His social interaction with others improved, his cognition, understanding, verbal skills, hyperactivity, and overall behavior improved. Above all, he was noticeably happier and exhibited less stress. Commenting on the TRH test, his mother voiced the conviction of so many mothers, “this one test has changed his life.”