What long-term effect is associated with untreated congenital hypothyroidism?

Untreated congenital hypothyroidism can lead to significant long-term effects, the most notable of which is cognitive impairment. This condition occurs due to a deficiency of thyroid hormones during critical periods of brain development in infancy and early childhood. When thyroid hormone levels are insufficient, it can disrupt normal growth and maturation processes in the brain, ultimately resulting in intellectual disability and learning difficulties.

Early diagnosis and treatment with thyroid hormone replacement therapy can effectively mitigate these risks, emphasizing the importance of newborn screening programs to detect hypothyroidism early. Addressing this condition promptly can help ensure that affected children develop cognitive and motor skills in line with their peers.

Other options, while related to thyroid dysfunction, do not specifically pertain to the long-term consequences of untreated congenital hypothyroidism. For example, myxedema is a condition typically associated with severe hypothyroidism in adults, not in untreated congenital cases. Thyrotoxicosis pertains to an excess of thyroid hormones, which is not relevant here. Spastic paralysis is a separate neurological condition and is not a direct consequence of untreated congenital hypothyroidism.