[Pyridoxal phosphate and activity of pyridoxalkinase in serum of preterm and term infants (author's transl)].

Vitamin B6 nutriture was measured in 14 preterm infants (born between 30th and 35th week of gestation) by means of determination of pyridoxalphosphate and activity of pyridoxalkinase in serum on the 1st and 4th day of life. 11 term infants were included as control group. At the 1st day pyridoxalphosphate and activity of pyridoxalkinase in preterm infants were significantly decreased in comparison with the control group. 50% of preterm infants--all were delivered before the 33rd week of pregnancy--did not show any activity of pyridoxalkinase in serum. On the 4th day, vitamin B6 nutriture of preterm infants was still decreased in comparison with the control group. Measurable activity of pyridoxalkinase, however, was now found in all preterm infants. There was a positive correlation at the 1st and 4th day of life between pyridoxalphosphate and weight and activity of pyridoxalkinase and weight. According to our results pyridoxalkinase is an enzyme which depends on the gestational age of the newborn. After the 32nd week of gestation the enzyme becomes active. Moreover pyridoxalkinase is an enzyme that can be induced by formulas containing vitamin B6. We consider the administration of vitamin B6 to the preterm infant as necessary.