Urine screening of five-day-old newborns: metabolic profiling of neonatal galactosuria.

We determined urinary galactose and 4-hydroxyphenyllactic acid (4HPLA) in 4338 of 5-day-old newborns using a newly developed GC-MS screening method. Fifty-two infants were chemically diagnosed as having transient galactosuria based upon elevated urinary galactose levels (4.78-30.53 mg/mg creatinine, control 1.10 +/- 0.89 mg/mg creatinine). These infants did not excrete galactitol or galactonic acid into the urine, which is typical of hereditary galactosemia. Nearly 40% of the transient galactosuria was associated with immature infants (low birth weight or borne before 37 gestational weeks). Immature hepatic function is one explanation for neonatal transient galactosuria, but heterozygotes or the carriers of galactose degradation enzyme deficiencies were also suspected in some of the newborns, judging from the comparisons of urinary galactose and 4HPLA excretion between neonates and patients with galactosemia.