Urinary phenolic acid and alcohol excretion in the newborn

Mean urinary excretion values of some phenolic acids and alcohols have been measured by gas chromatography in 44 neonates (36 males, 6 females) during the first 2 days and days 3-7 of life, and the effect of prematurity and jaundice assessed. 4-Hydroxy-3-methoxymandelic acid (VMA) output rises immediately after birth in term but not in preterm infants. A similar increase in homovanillic acid (HVA) output was restricted to nonjaundiced term babies; in nonjaundiced preterm babies there was a steady rise during the first week. The ratio of HVA to VMA output was higher in these infants than in adults, suggesting a more rapid turnover of dopamine than adrenaline and noradrenaline. Unlike adult values, both HVA and VMA excretion values were directly related to urine volume, an observation perhaps related to renal immaturity. An unexplained reduction in HVA output in jaundiced as opposed to nonjaundiced infants was observed in the first 2 days of life. The ratio of 4-hydroxy-3-methoxyphenylglycol to VMA was about the same as in the adult. p-Hydroxyphenyl-lactic acid (p-HPLA), because of its superior stability, was measured in preference to p-hydroxyphenylpyruvic acid as an index of tyrosyluria. An output of 1 mg p-HPLA/24 h is proposed as the upper limit of normal. Prematurity was associated with a significant rise in p-HPLA output. A dramatic increase in excretion of this acid was noted in jaundiced, compared with nonjaundiced infants, presumably a manifestation of general enzyme immaturity.