Congenital hypothyroidism is a condition that affects infants from birth and results from a missing or abnormally developed thyroid gland, abnormal production of thyroid hormones or a failure of the pituitary gland to stimulate thyroid hormone production. It affects approximately 1 in 3000 to 4000 newborn infants and early diagnosis and treatment is very important to achieve a good outcome.Treatment of congenital hypothyroidism consists of a daily dose of thyroid hormone (thyroxine). However, the initial dose of thyroxine required to improve outcomes for infants with this condition is unclear and has been the subject of several studies. Some studies have suggested that when infants with congenital hypothyroidism are treated with a higher dose of thyroxine compared with the standard dose, this results in earlier normalisation of the their thyroid hormones and leads to better developmental outcome and intelligence.
There is currently only one study reporting on 47 babies that fulfils our review criteria and compares different high dose versus low dose of initial replacement thyroxine for the treatment of congenital hypothyroidism. There is not enough evidence to suggest that a high dose is more beneficial than a low dose therapy. Growth and adverse effects were not reported in the included study. There should be more randomised controlled trials to assess the effects of high versus low dose of initial thyroid hormone replacement for congenital hypothyroidism.