Heather

Thyroid Functioning and Risk of Childhood Autism Heather M. Barrow, M.P.H H. Patrick Stern, M.D. Tiejian Wu, M.D., Ph.D.

Introduction  Autism is a neurobiological disorder of a complex developmental disability that has to appear during the first 3 years of life.  Individuals with autism have problems with social interaction, communication difficulties, and restrictive or repetitive interests/behaviors.

Introduction  Recent studies by the National Institute of Health – One out of 250 children born in the United States has some degree of autism. – The risk increases to about one in 25 if the child has a brother or sister with the condition.

 It is generally accepted that autism includes abnormalities in the brain structure or physiological function, while the causes for the abnormalities are not clear.

Introduction  Abnormal thyroid function can have a variety of behavioral effects, ranging from severe neuropsychological defects in children with congenital hypothyroidism to hyperactivity associated with hyperthyroidism.  The purpose of this study is to examine the association between thyroid function and risk of childhood autism. – If there is an association, this will allow for the possible consideration of a therapeutic treatment of thyroid.

Review of the Literature  There have been a few studies that have examined the relationship between thyroid hormone and autism status. – A study conducted in 1980 by Cohen et al. evaluated the blood indices of thyroid function, including T4, T3, and TSH, in a larger population of autistic children.  No differences were found between autistic and normal children.

– Another study conducted by Hashimoto et al. in 1991 showed that mean TSH basal levels, mean TSH peak levels, and mean TSH peak values minus basal values were significantly lower in autistic children than in the control group.

Review of the Literature  One study that has recently investigated the relationship between neonatal measure of thyroid and autism in children. – This study conducted by Soldin et al. in 2003 found that there were no significant differences that were detected between neonatal (T4) values in the cases of autistic spectrum disorder and the controls.  All neonatal T4 values were within normal ranges.

Summary  There is a biological possibility that thyroid hormone may play a role in the development of autism.  There is no consistency amongst these few studies on whether or not there is a relationship between thyroid hormone and autism status.  Further investigation needs to be done in order to see if there is a possible relationship between thyroid hormone and autism.

Methods  Community Care Wellness Center  The parents of 88 children diagnosed with autism were contacted by mail and phone. – Packets-cover letter and informed consent form – Phone-an initial and a follow-up phone call

 Medical charts were reviewed. – Chart review - Parent questionnaire – Lab tests-Current TSH, T4, Free T4, T3, Free T3, Lead, Ferritin, and Genetics

 Collect neonatal TSH levels from the Tennessee neonatal screening program.

Methods  A database was created to sort the 88 patients into categories. – 70 of the parents were contacted by phone.  18 phone numbers were disconnected

– 3 of the addresses were wrong – 10 participants refused to participate

Methods  Number of eligible patients = 57 (age range of 1- 15 years old). – 23 (40%) informed consents were received

 The lab results were tabulated in a spreadsheet in relation to specific reference values.

Results

T SH MEDIA N =3.45

0.617

Individual (1 - 15 years old)

0.8 0.97 1.028 Average = 1.36 1.39 2.87 1.96 0.6

1.6

2.6

3.6

4.6

R e fe re nce R ange (0.6 - 6.3 mIU/mL)

5.6

T3 MEDIA N=167.5

MEDIA N=187

Individual (1 - 10 years old)

105

160

94

114

134

154

174

194

214

R e fe re nce R ange (94 - 269 ng/dL)

234

254

Free T3

MEDIA N=4.215

Individual (1 - 9 years old)

4.06

Average = 4.225

4.225

3.37

3.57

3.77

3.97

4.17

4.37

4.57

Re fe re nce Range (3.37 - 5.06 pg/mL)

4.77

4.97

T4 7.3 MEDIA N=11.15

Individual (1 - 5 years old)

9.6

Average = 9.725

11.1

10.9

7

8

9

10

11

12

R e fe re nce R ange (7.3 - 15 mcg/dL)

13

14

15

Free T 4 1 MEDIA N=1.2

Individual (> 10 days old)

1.1

1.1

1.1

Average = 1.138

1.39 0.7

0.8

0.9

1

1.1

1.2

1.3

1.4

R e fe re nce R ange (0.7 - 1.7 ng/dL)

1.5

1.6

1.7

Lead 1 1

MEDIA N=5

1

Individual (child)

1 2 2 2 A verage = 2.52 3 6.2 6 0

1

2

3

4

5

6

7

R e fe re nce R ange (< 10 mcg/dL)

8

9

10

Ferritin 8 11

Individual (6 months - 15 years old)

11

MEDIA N=73.5

15 16.7 A verage = 20.3 22 22 23.1 25 35 35 7

27

47

67

87

R e fe re nce R ange (7 - 140 ng/mL)

107

127

Discussion  This pilot study was able to observe several trends from the collected data.  Current TSH levels tended to be on the lower end of the normal range  More data is needed to show the patterns of T3 and T4.  This may indicate that thyroid hormone may play a role in the risk of childhood autism and deserves further research attention.

Discussion  This study has several limitations. – Small sample size of only 23 – All study subjects are males  Only 7 of the eligible 57 patients were female.

– Normal range was used, but a control group was not available. – Not all of the patients had all of the lab results – This study was not able to retrieve the neonatal thyroid levels at this time.  These levels will be retrieved at a later date in order for this study to be complete.

Conclusion  This pilot data indicates that there could be a possible correlation with thyroid functioning and risk of childhood autistic spectrum disorder.  A better understanding of autism will help in better prevention and treatment strategies.  Further investigation is needed in order to better understand the etiology of autism.