Cerebrospinal fluid transthyretin in the neonate and blood-cerebrospinal fluid barrier permeability.

We measured transthyretin levels in the cerebrospinal fluid (CSF) of newborn infants, older children, patients with viral and bacterial meningitis, and adults with increased CSF protein levels. Neonatal CSF transthyretin levels are elevated disproportionately in comparison to levels in the other groups. We conclude that increased levels of transthyretin in the CSF of neonates are not explained by increased permeability of the blood-CSF barrier.