title: Should the levothyroxine starting dose be tailored to disease severity in neonates with congenital hypothyroidism?
abstract: Early levothyroxine treatment is crucial to minimize neurocognitive impairment associated with congenital hypothyroidism. In this Practice Point commentary, I discuss the findings, implications, and limitations of the study of Mathai et al. in which neonates with congenital hypothyroidism were treated with variable initial doses of levothyroxine. A high initial levothyroxine dose was used for newborn babies with athyreosis, an intermediate dose for those with ectopic glands, and a low dose for those with dyshormonogenesis. Serum free T(4) levels normalized within 2 weeks, but serum TSH levels within up to 4 weeks. A dose adjustment (mostly a dose reduction) was required in about half of the neonates in the first 2 weeks of life. As Mathai et al. carried out no neuropsychological tests, we do not know if their approach has a more beneficial effect on neurocognitive outcomes than other treatment strategies. Nevertheless, as tailoring the levothyroxine dose to severity rapidly normalized serum free T(4) levels, one would predict a beneficial effect of this approach on neurocognitive outcome.
authors.affiliation: Department of Pediatrics, Oregon Health and Science University, Portland, OR 97239, USA. lafrancs@ohsu.edu
authors.forename: Stephen H
authors.initials: SH
authors.lastname: LaFranchi