The clinical effects of transient elevation of serum tyrosine level were evaluated in a group of premature infants. Neurologic performance was measured at 15 to 29 months of age using the Bayley Infant Scale of Mental Development. There were no differences in either motor or mental development as measured by this test between infants with high and low serum tyrosine levels.
The neonatal course in infants with elevated serum tyrosine levels was compared to that in two groups of infants with low serum tyrosine levels: one group with and one without supplemental ascorbic acid. The only difference in the occurrence of maternal or neonatal complications was in the group with high tyrosine levels, which had significantly greater incidence of symptoms similar to those in infants with neonatal sepsis and characterized by lethargy, poor feeding, and failure to gain weight.