Pyridoxal phosphate in plasma and leukocytes of normal and pregnant subjects following B6 load tests.

SummaryA method for determination of pyridoxal phosphate in human plasma is described. The amount of coenzymatically active form of Vit. B6 was determined simultaneously in blood of normal subjects, delivering women, and in cord blood of their babies. In general, amounts of pyridoxal phosphate in plasma and leukocytes showed parallel changes. They were low in maternal blood, and high in cord blood. Following oral administration of 100 mg pyridoxine hydrochloride, increases were observed in both plasma and leukocytic B6 values within a few hours. Considerably higher peaks were seen in normal controls as compared to women in last trimester of pregnancy and at time of delivery. The most significant difference between pregnant and nonpregnant subjects was noted in plasma values 24 hours following administration of vitamin. The possible practical application of these findings for evaluation of a latent B6 deficiency in clinical subjects is suggested.