Neonatal thyroid hormone levels in association with autism spectrum disorder.
Newborn thyroid levels from the heel-stick screen do not forecast later autism.
01Research in Context
What this study did
Doctors already collect a few drops of blood from every newborn’s heel. The team asked if the thyroid numbers in that spot of blood can tell us who will later get autism.
They pulled the newborn screen cards for the children already diagnosed with ASD and 6,000 matched peers. Then they compared TSH and T4 levels.
What they found
After accounting for sex, birth weight, and lab batch, thyroid levels looked the same in both groups.
Only babies whose blood was taken after 48 hours showed a tiny bump in odds, and that signal was weak.
Bottom line: the routine heel-stick thyroid test does not predict autism risk for most newborns.
How this fits with other research
Nicholson et al. (2017) lines up with Griffith et al. (2012). Both used case-control blood tests and found nothing useful. One looked at neonatal thyroid; the other looked at adult serotonin. Together they show simple single-spot blood markers rarely separate ASD from controls.
Rana et al. (2024) seems to clash at first. They found neonatal jaundice raises sensory red flags in preschoolers with ASD, while Kristen found no thyroid signal. The difference is exposure type: jaundice is a longer body stress, thyroid is a one-time lab value. Short lab snapshots may miss what longer stress leaves behind.
Nygren et al. (2012) screened toddlers at 24 months and quadrupled ASD prevalence. Their work shows early detection is possible, but it takes behavioral screening, not newborn chemistry.
Why it matters
You can stop hunting for autism clues in the standard thyroid numbers already printed on newborn screens. Instead, use that time to watch for clearer risk flags like jaundice, maternal anxiety, or delayed social milestones, and refer for early behavioral screening when you see them.
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02At a glance
03Original abstract
Thyroid hormones (TH) are critical in early neurodevelopment, but few studies have examined whether neonatal TH levels influence risk of autism spectrum disorder (ASD). This study linked California neonatal screening data with live birth and Department of Developmental Services records to examine newborn TH levels in relation to ASD. Thyroxine (T4) and thyroid-stimulating hormone (TSH) levels were measured in newborn bloodspots as part of routine screening, in 1996 and 2002, respectively. Mean levels of T4 and TSH were compared between ASD cases and non-cases. Four hundred forty-seven thousand, fifty-nine screened, singleton births from 1996 and 446,424 from 2002 were examined, including 4,818 ASD cases. Binomial regression, using categories of T4 and TSH percentiles was used to calculate crude and adjusted risk ratios (RR). Covariates included maternal and child factors, gestational age, and age at blood draw. No significant associations were found with TSH levels and ASD in crude or adjusted analyses. ASD cases had significantly lower mean T4 levels than non-cases, but this association was no longer significant in adjusted analyses (RR in individuals in lowest 5th percentile of T4 levels = 1.13, 95% 0.93-1.37). However, this association appeared stronger in certain subgroup analyses, particularly among neonates with blood draw ≥48 hr from birth (RR = 1.67, 95% CI 1.08, 2.60), when TH levels become more stable. Thus, results from this large, population-based study did not suggest strong associations between neonatal TH and ASD, but certain subgroups of newborns with the lowest T4 levels may have modestly increased ASD risk. Autism Res 2016. © 2016 International Society for Autism Research, Wiley Periodicals, Inc. Autism Res 2017, 10: 585-592. © 2016 International Society for Autism Research, Wiley Periodicals, Inc.
Autism research : official journal of the International Society for Autism Research, 2017 · doi:10.1002/aur.1708