Association between borderline neonatal thyroid-stimulating hormone concentrations and educational and developmental...

Area of Science:

• Neonatal screening
• Endocrinology
• Developmental pediatrics

Background:

• Congenital hypothyroidism (CH) can cause intellectual disability if untreated.
• Newborn screening effectively prevents most CH-related intellectual disability.
• Clinical uncertainty exists for infants with thyroid-stimulating hormone (TSH) levels below screening cutoffs.

Purpose of the Study:

• To assess the association between neonatal TSH concentrations and later educational and developmental outcomes.
• To investigate potential risks for infants with TSH levels below current newborn screening thresholds.

Main Methods:

• Population-based record-linkage study of over 500,000 infants in New South Wales, Australia (1994-2008).
• Linked newborn screening TSH results with educational (NAPLAN) and developmental (Australian Early Development Census) outcomes.
• Excluded very-low-birthweight infants; used multivariable logistic regression to control for confounders.

Main Results:

• Infants with TSH levels between the 99.5th and 99.9th percentile showed increased odds of special needs, poor numeracy, and developmental risk.
• Infants with TSH levels at or above the screening cutoff (likely diagnosed CH) had outcomes similar to those with low TSH levels.
• A dose-response relationship was observed between increasing TSH percentiles and poorer outcomes.

Conclusions:

• Neonatal TSH concentrations below current newborn screening thresholds are associated with adverse educational and developmental outcomes.
• Further research is needed to determine if targeted assessment and treatment for these infants can improve long-term cognitive function.