Thyroid hormone in autistic children.

Doctors drew blood from 20 autistic kids and 20 matched peers. They checked T3, T4, and TSH levels. The lab work happened in 1980, before modern autism criteria.

No pills or diets were given. The team just wanted to know if thyroid numbers looked different.

All hormone levels landed in the same range for both groups. High, low, or middle scores showed up equally in each child set.

The authors wrote: "Thyroid function is not a useful marker for autism."

Lalli et al. (1995) ran the same null play with androgens. They also found no group gap, backing the idea that basic blood hormones rarely flag autism.

Hranilovic et al. (2007) looks like a clash — they saw high platelet serotonin in autistic adults. The gap is simple: different chemical, older sample. Kids’ thyroid and adults’ serotonin can both be normal in their own studies without conflict.

Goldberg et al. (2009) moved the hunt to parents’ brains, finding lower serotonin-2 receptors. Together these papers show the field keeps testing biology, yet single blood draws keep coming up empty.

You can skip thyroid panels when diagnosing autism. Save families time and money. If a child shows slow growth or fatigue, run the test for medical care, not for autism clues. Focus your assessment on behavior and development, not routine hormone screens.