What is a notable effect of untreated congenital hypothyroidism?

The notable effect of untreated congenital hypothyroidism is the potential to cause mental retardation, also referred to as intellectual disability. This condition arises from insufficient thyroid hormone levels during critical periods of brain development in infants. Thyroid hormones are essential for normal neurological development; without them, the brain does not mature properly, which can lead to cognitive impairments.

In congenital hypothyroidism, if treatment does not commence early—ideally during the first few weeks of life—the risks for developmental delays, intellectual disabilities, and other neurocognitive issues significantly increase. Addressing this condition promptly with thyroid hormone replacement therapy is crucial for preventing or minimizing these serious outcomes. Early detection through newborn screening programs plays a vital role in mitigating the risks associated with this disorder.