Expanded newborn screening for detection of vitamin B12 deficiency.

摘要

To the Editor: When undiagnosed, infant vitamin B12 deficiency can result in anemia, failure to thrive, developmental regression, and neurological deficits and is most commonly caused by maternal vitamin B12 deficiency.1 Biochemically, vitamin B12 deficiency leads to an accumulation of total homocysteine (tHcy), methylmalonic acid (MMA), and propionylcarnitine (C3). Although vitamin B12 deficiency is not a primary target of newborn screening (NBS) programs, measurement of C3 may incidentally identify vitamin B12-deficient newborns. However, first-tier screening is limited because C3 levels may not be sufficiently high during the first days of life when most NBS samples are collected