Urinary organic acid excretion by babies born before 33 weeks of gestation.

Using analytical procedures that are widely used by laboratories investigating metabolic disorders, we investigated urinary organic acid excretion by premature neonates who were receiving the usual clinical care. Our purpose was to provide a basis for the diagnosis of inherited organic acid defects. We analyzed 127 random (untimed) urine samples collected weekly from 22 infants of 25-32 weeks of gestation (median, 28 weeks). A wide variety of organic acids was excreted. After oximation, they were extracted with ethyl acetate and diethyl ether, derivatized to trimethylsilyl forms, and analyzed by gas-liquid chromatography on a nonpolar fused silica capillary column, with mass spectrometry for identification. Profiles for individual babies varied markedly on different occasions, reflecting their metabolic status and bacterial activity in the gut. There was no significant ketonuria. Three metabolites identified for the first time in urine from normal neonates were 2,3-butanediol, 3-hydroxy-2-butanone (acetoin), and 4-hydroxy-3-methoxyphenyllactic acid. Significantly increased excretion of 4-hydroxyphenyllactic acid and other phenolic acids occurred during parenteral feeding.