Distribution of riboflavin in blood: in women and in prenates.

The reliability of the photodecomposition method for riboflavin in various constituents of blood is demonstrated by recovery tests in vivo. In normal subjects no significant rise in whole blood, erythrocyte or plasma riboflavin is detected 2 hours after oral treatment. With intervenous therapy a rise occurs in plasma riboflavin and not in erythrocytes. In kidney disease after oral riboflavin unusually high sustained plasma levels are recorded with no change in erythrocyte levels. Correspondingly higher erythrocyte riboflavin concentration in cord blood as compared to that of maternal blood may indicate greater avidity of new fetal cells for riboflavin.