Low thyroid function has long-lasting effects

NEW YORK (Reuters Health) - Newborn babies are routinely screened for low thyroid hormone levels. When the condition -- congenital hypothyroidism -- is discovered, its severity influences long-term mental performance and movement function, new research shows.

The hope has been that early treatment of hypothyroidism will prevent development problems, but the study found that the timing of the start of treatment does not seem to have a great effect.

"This study has shown that cognitive and motor deficits in congenital hypothyroidism patients, who started treatment at a median age of 28 days after birth, persist into adulthood," the researchers write in the Journal of Clinical Endocrinology and Metabolism.

The findings are based on a study of 70 young adults who had been diagnosed with hypothyroidism during neonatal screening.

Compared with the normal population, patients with congential hypothyroidism had significantly worse motor and cognitive function scores, Dr. M. J. E. Kempers, from the University of Amsterdam in the Netherlands, and colleagues note.

In general, IQ from childhood held steady into adulthood, the report indicates. On further analysis, the severity of congenital hypothyroidism correlated with IQ and motor deficits, whereas the timing of treatment initiation did not, the investigators report.

The results suggest that "mildly and moderately affected patients have a fair prognosis, whereas severely affected congenital hypothyroidism patients continue to experience IQ and motor problems in later life," the authors conclude.

SOURCE: Journal of Clinical Endocrinology and Metabolism, February 2006.