Studies on Phenylketonuria. V. Observations on a Newborn Infant with Phenylketonuria.

Biochemical studies have been performed on a phenylketonuric infant from birth to the age of 34 days. Cord blood and newborn infant blood contained normal levels of phenylalanine, the serum phenylalanine rose to 62 mg % at 24 days, and decreased to 41% at 34 days. Phenylpyruvic acid was not excreted in detectable amounts until 34 days. o-Hydroxyphenylacetic acid was not present in excess at 5 days, but from 16 to 34 days was excreted at about one-fifth the rate usually observed in phenylketonuria. The minor abnormal metabolites indolelactic and p-hydroxyphenyllactic acids were not present at 5 days, but were present at 16 days.